text: by R.R.Lutz ^ A guide fo Ike use of graphic methods in business MODERN INDUSTRY IOOKS GRAPHIC PRESENTATION SIMPLIFIED ByR. R. LUTZ A MODERN INDUSTRY BOOK A practical guide to the use of modern graphic methods in business, this new book shows you how to present facts in their most simple visual form . . . how to make all kinds of graphic charts . . . how to use them . . . how to analyze a problem, select the equipment and execute the graph or graphs best suited to the problem. Detailed information is given on: Curve charts Bar charts Circle charts Sector charts Statistical map charts Dot maps Pin and tack maps Flow maps the use of color. Invaluable for businessmen, managers and ex- ecutives, as well as clerical workers and statis- ticians, this book will enable you to analyze and record the operations of your business. In addition, the book offers a training program for beginners who must depend on their own efforts without skilled supervision, with clear instructions in layout and plotting, and exam- ples for practice. FUNK & WAGNALLS COMPANY 153 East 24th Street New York 10. N. Y. From the collection of the n m o Prelinger i a AJibrary t P San Francisco, California 2006 GRAPHIC PRESENTATION SIMPLIFIED MODERN INDUSTRY BOOKS Your Public Relations GLENN GRISWOLD AND DENNY GRISWOLD Standard Business-Conference Technique CARL HEYEL How To Reduce Distribution Costs RICHARD D. CRISP Practical Handbook of Industrial Traffic Management RICHARD c. COLTON Management Controls for Foremen and Supervisors HARRY j. MCCAULLY, JR. The Law of Free Enterprise LEE LOEVINCER Bargaining with Organized Labor RICHARD c. SMYTH AND MATTHEW j. MURPHY Supervision in Business and Industry ROBERT D. LOKEN AND EARL p. STRONG Wage Policy for Management SUMNER D. CHARM Our New National Labor Policy FRED A. HARTLEY, JR. Tested Techniques in Labor A rbit ration GEORGE w. TORRENCE The Economics of Industrial Management WALTER RAUTENSTRAUCH AND RAYMOND VILLERS Foundations for Constructive Industrial Relations R. CARTER NYMAN Management Men and Their Methods LUIS j. A. VILLALON Graphic Presentation Simplified R. R. LUTZ How To Cut Production Costs H. E. BLANK, JR. Teamwork in Industry WILLIAM SEWARD How To Sell to Latin America ABRAM A. PRECIADO BY R. R. LUTZ FUNK & WAGNALLS COMPANY NEW YORK m association with MODERN INDUSTRY MAGAZINE NEW YORK COPYRIGHT, 1949, BY MAGAZINES OF INDUSTRY, INC. 1 COPYRIGHT UNDER THE ARTICLES OF THE COPYRIGHT CONVENTION OF THE PAN AMERICAN REPUBLICS AND THE UNITED STATES PRINTED IN THE UNITED STATES OF AMERICA ACKNOWLEDGMENTS THE AUTHOR wishes to express his deep appreciation for the help received in the preparation of this volume from fellow workers with whom he has been associated in the course of nearly twenty years' experience in graphic design and presentation. He wishes also to thank the business firms and associations which have made available for in- clusion in the book many of the graphic examples used as illustrations in the discussions of methods and principles. He is especially indebted to Mr. Willard C. Brinton for his helpful advice and counsel during the planning stage of the volume. Grateful thanks are due Mrs. Mabel Howell for her painstaking aid in the preparation of the charts and other illustrations for publication. CONTENTS ACKNOWLEDGMENTS v LIST OF ILLUSTRATIONS xi LIST OF TABLES xix CHAPTER PAGE I AN EXPANDING ART 1 Graphic Presentation in Two World Wars Charts Versus Tables Improvements in Equipment Re- duction in Length of Training Training Methods II CURVE CHARTS 10 Designation of Chart Components Titles Abbrevi- ations for Time Scales Proportions of Width and Height Scale Numbers Position and Labeling of Scales Scale Rulings Curve Patterns Omission of Zero Base 100 Percent Base in Index-number Charts Break in Time Scale Fitting Curves to Gain Space Omission of Time-scale Ruling Above Curves- Plotting Points Moving-average Curves Weight of Grid Lines Broken Curve Stock-price Charts Cu- mulative-curve Charts Multiple-scale Charts Mul- tiple-time-scale Charts Staircase-curve Charts Keys vii viii CONTENTS CHAPTER PAGE III SURFACE-CURVE CHARTS 32 Differentiation of Trends by Shading Strata Charts Distortion Produced by Steep Curves Use of Shad- ing to Show Net Results Shading Significant Time Periods Contrasting Net Changes Miniature Sur- face-curve Charts Long-range Business - activity Charts Shaded Staircase-curve Charts Shading Versus Solid Black Economy of Space in Design IV RATE-OF-CHANGE CHARTS 44 Grid Ruling Omission of Scale Rulings Rate-of- change Versus Index Numbers Methods for Laying Out Grids Explanatory Note Units Varying in Size and Kind Limited Use of Rate-of-change Designs V BAR CHARTS 54 Wide Range of Values Lettering Versus Scales- Order of Components and Ruling Lettering Stub on Bars Joined-bar Charts Grouped-bar Charts Keys Paired-bar Charts Bar-and-symbol Charts Area- bar Charts Optical Distortion in Bars Inclusion or Omission of 100 Percent Base Deviation-bar Charts Base Figures in Charts of Relative Numbers Adjustment of Stub to Space Step-bar Charts Sliding-bar Charts VI COLUMN CHARTS 76 Column and Segment Labels Comparison of Col- umns with Curves Hollow Columns Combination of Spaced and Joined Columns Combination of Chart and Table Grouped-column Charts Com- bination of Columns and Curves Charts Showing Both Basic Data and Percentage Distribution Devi- . ation-column charts VII CIRCLE CHARTS 90 Common Errors in Drafting Circles Short-cut Meth- od for Calculating the Size of Circles Circles Com- pared with Bars CONTENTS ix CHAPTER PAGE VIII SECTOR CHARTS 96 Order of Sectors Lettering of Sector Charts Group- ing of Sectors Miniature Sector Charts Separation of Sectors for Emphasis Omission of Shading Sec- tor Totals IX STATISTICAL MAP CHARTS 104 Use of Colors Maps with Surface Designations of Categories Dot Maps Maps with Circles Maps with Columns, Bars, or Curves Pin and Tack Maps Flow Maps Keys X PICTORIAL CHARTS 112 Bar Pictorial Charts XI MISCELLANEOUS TYPES 116 Ranking Charts Frequency - distribution Charts Relative-variation Charts Organization Charts Comparison of Equal Amounts with Circles Circu- lar-bar Design XII ELEMENTARY TRAINING METHODS 127 Charts on Printed Graph Paper Typewritten Charts XIII SMALL CHARTS ON UNRULED PAPER 132 Equipment Grid Lay-out Types of Scales Joined- bar Lay-out Spaced-bar Lay-out Column-chart Lay-out Curve-chart Lay-out and Plotting Circle- and Sector-chart Lay-out Lettering Paper Inking Order of Operations XIV DISPLAY CHARTS 146 Use of Color Lay-out and Equipment Lettering- Paints Crayons Airbrush Coloring Rolled Charts Mounting on Cardboard XV REPRODUCTION PROCESSES 153 Photostat-Photo-offset-Multilith-Stencil and Gela- tin Duplicators Enlargements Reductions x CONTENTS CHAPTER PAGE XVI CLASSIFICATION OF CHARTS BY USE 160 Charts for Publication Charts for Inter-office Distri- butionCharts for Desk Use Charts for Conferences, Board Meetings, and Hearings Chart Exhibits Charts for Public Addresses Charts for Recording Current Operations XVII STATISTICAL PROCEDURES 175 Rounding Averages Weighted Average Frequency Distributions Index Numbers XVIII PLANNING, TABULATION, AND PRESENTATION OF TABLES 189 Tabulating Sheets-Units of Value-Titles-Stubs- TabulationColumn Widths Capitalization Punc- tuation Symbols Ruling INDEX 197 LIST OF ILLUSTRATIONS CHARTS CHART PAGE 1 Reduction in Schedules of Production, Combat Planes: December, 1917, through February, 1918 2 2 Balance of Construction and Sinkings, British Merchant Marine: 1914 to 1916 4 3 Designation of Chart Components 11 4 Effects of Scale Alterations 12 5 Too Much Ruling 16 6 Ruling Replaced by Ticks 16 7 Combination of Ticks and Ruling 16 8 Curve Patterns 17 9 Omission of Zero Base 19 10 Wages, Prices, and Production 20 11 Retail Cost of Food: 1939, 1944, and 1945 21 12 Depression, Recovery, Depression 23 13 Stocks of C, D, and K Emergency Rations: 1943 24 14 Plotting to Space or Line 25 15 Business Failures 26 16 Placements by U.S. Employment Service: 1937 to 1945 27 xi xii LIST OF ILLUSTRATIONS CHART PAGE 17 Broken Curve 28 18 Stock-price Chart 29 19 Cumulative-curve Chart 29 20 Multiple-time-scale Chart 30 21 War Appropriations: 1917-18 and 1940-41 31 22 Depression and Recovery 33 23 Production of Motor Trucks and Truck Tractors: 1936 to 1945 34 24 Distortion Produced by Steep Curves Rising or Falling at a Uniform Rate 35 25 Average Weekly Earnings of Wage-earners in Manufac- turing, and Consumers' Price Index: 1939 to 1945 36 26 Money in Circulation, United States, Per Capita: 1916 to 1945 37 27 Immigrant Aliens Admitted and Departed: 1932 to 1945 38 28 Tonnage Received and Shipped by QMC Depots: 1944 39 29 American Business Activity 40 30 Employment and Unemployment, United States: 1929-1939 41 31 Hours Spent in the Air by American Service Planes at the French Front During World War I 42 32 Volume of Production, United States: 1859 to 1934 43 33 Arithmetic and Rate-of-change Scales 45 34 Top and Bottom of Cycle Omitted 46 35 Growth of Population, Puerto Rico and Hawaii: 1930 to 1940 47 36 Method for Laying Out Rate-of-change Grids with Log- arithmic Paper 48 37 Scale for Laying Out Rate-of-change Grids 49 LIST OF ILLUSTRATIONS xiii CHART PAGE 38 Industrial Contributions of Science and Invention, United States: 1830 to 1930 51 39 Arithmetic, Logarithmic, and Index Log Charts 52 40 Receipts of Wheat at Primary Markets: 1943 55 41 Crime Rates in Urban Communities, by Geographic Divi- sions: 1943 (Data Scaled) 56 42 Crime Rates in Urban Communities, by Geographic Divi- sions: 1943 (Data Lettered on Bars) 57 43 Lettering Within and At the End of Bars 58 44 Post, Camp, and Station Stocks of Non-perishable Subsis- tence Items 59 45 Federal Expenditures Per Capita 60 46 Population of Five Largest States: 1940 61 47 Index of Stocks, Secondary Items 62 48 Two Methods for Placement of Keys 63 49 Net Income or Deficit of Governmentally Owned or Op- erated Railways in Various Foreign Countries: 1935 or 1936 64 50 Contractor-owned Termination Inventory 65 51 Proportion of Working Population Covered by the Old Age Provisions of the Social Security Act, Using the 'Dis- tribution of Occupations of the 1930 Census 66 52 Optical Distortions 67 53 Inclusion or Omission of 100 Percent Base 68 54 Price Changes 69 55 Army Funds Uncommitted 70 56 Consumers' Prices 71 57 Estimated Non-agricultural Employment, Five Largest In- dustrial Groups: Last Quarter, 1945 72 xiv LIST OF ILLUSTRATIONS CHART PAGE 58 Exports (Including Reexports), United States, by Conti- nents: 1940 73 59 Loans and Investments of the Member Banks of the Fed- eral Reserve System from 1929 to 1935 74 60 Disposition of Surplus Property: June to December, 1944 77 61 Instalment Credit: 1939 to 1945 (Column Design) 78 62 Instalment Credit: 1939 to 1945 (Curve Design) 79 63 Men Sailing Each Month to France and Home: 1917 to 1919 80 64 Industrial Production, Manufactures: 1939 to 1945 81 65 Industrial Production 82 66 Heavy and Light Bombers Accepted: 1942 83 67 Par and Market Values of Bonds Sold on New York Stock Exchange: 1938 to 1945 84 68 Receipts, Expenditures, and National Debt 85 69 Method for Lettering Basic and Percentage Figures on Col- umn Charts 86 70 Interest Payments on Debt of Federal, State, and Local Governments: 1932 and 1945 87 71 Total Exports and Imports of Merchandise: 1915, 1925, 1935, and 1945 88 72 Domestic Corporate Security Issues 89 73 Use of Different Geometric Forms in Comparing Sizes 91 74 New Industries and Employment (Circle Design) 94 75 New Industries and Employment (Bar Design) 95 76 Comparison of Sector and Bar Charts 97 77 Imports, United States, by Economic Classes: 1942 98 78 Contract Awards to Small Firms: 1944 99 79 Composition of National Guard Divisions, World War I 100 LIST OP ILLUSTRATIONS xv CHART PAGE 80 Causes of Delays in May Deliveries, Signal Corps: 1942 101 81 Distribution of Male Labor Force 14 Years Old and Over, United States: 1940 102 82 Military Expenditures, United States: 1939 103 83 Percent of Drafted Men Passing Physical Examination, by States, World War I 105 84 Number of Contracts Awarded in Each State in 1944 106 85 Rural Rehabilitation Cases Receiving Advances of Capital or Goods: 1935 107 86 Distribution of Florida Grapefruit in the 1932-33 Season 109 87 Typical Distribution of Employees in a Large Telephone Company 113 88 Printed Symbols for Use in Bar Pictorial Charts 114 89 Outlook for Surplus Property Disposals 115 90 Rank of Commodity Groups Based On Wholesale Prices: 1939 Average and December, 1945 117 91 Rank of Each of the United States in Ten Educational Fea- tures: 1910 118 92 Estimated Population, United States, by Age Groups: 1945 119 93 Estimated Weekly Hours Worked, Non-agricultural Em- ployment: Third Quarter, 1945 120 94 Relative Monthly Variation Stocks, Selected Equipment Items: 1944 121 95 Relative Monthly Variation Non-perishable Subsistence Placed on Contract, Selected Items: 1944 122 96 Typical Organization-chart Design 123 97 The Deficit in Perspective 124 98 Exports, U.S. Merchandise, as Percent of Total Exportable Goods: 1909 to 1945 125 xvi LIST OF ILLUSTRATIONS CHART PAGE 99 Expenditures for New Private and Public Construction: 1934 to 1945 128 100 Employment of Women, Selected Durable Goods Indus- tries: 1941 and 1942 101 Use of Scale in Grid Lay-out 102 Vertical Distribution of Bars 103 Method for Plotting Amounts 104 Bars and Spacing in Spaced-bar Charts 105 Columns and Spacing in Spaced-column Charts 106 Plotting of Amounts on Column Charts 107 Curve-chart Lay-out 108 Circle- and Sector-chart Lay-out 109 Example of Stripped Title and Curve Labels 110 D. C. Building Boom 111 QMC Military Personnel 112 Employment and Average Weekly Hours, Wage-earners in Manufacturing: 1929 to 1937 182 113 Average Employment and Hours Worked 114 Production, Wholesale Price, and Value of Production 115 Output Per Man and Per Hour FIGURES FIGURE PAGE 1 Samples of Adhesive Screens 7 2 Map Tacks for Large Map Charts 3 Samples of Graph-paper Ruling 4 Triangular Decimal Scale LIST OF ILLUSTRATIONS xvii FIGURE PAGE 5 Tape Scales 135 6 Compass and Protractor 142 7 The Vari-Typer 143 8 Ruling Pen 144 9 Bow and Drop Pens 145 10 Drafting Table Fitted with Parallel Rule 148 11 Leroy Lettering Guide 149 12 Sample Lettering-guide Alphabet 150 13 Method for Stiffening Rolled Charts 152 14 Comparison of Negative and Positive Photostat Prints 154 15 Reduction of Lettering and Ruling 156, 157 16 Reduction of Elite Type 158 17 Portable Fixture for Exhibit of Small Charts 169 18 Wall Cross-section of a Chart Exhibit 171 19 Lantern-slide Projector 172 LIST OF TABLES TABLE PAGE I Root-two Dimensions 15 II Calculation of Circle Diameters 92 III Square Roots of Decimals-.Ol to .99 93 IV Simple Average 177 V Average of a Wide Range of Values 177 VI Arrangement of Values to Determine the Median 178 VII Weighted Average 178 VIII Simple Frequency Distribution 179 IX Class-interval Distribution 180 X Differences in Range of Class Intervals 180 XI Employment and Hours Worked Per Week, Manufacturing Industry: 1929 to 1937 182 XII Employment, Hours Worked Per Week, and Total Hours Worked: 1929 to 1937 183 XIII Production, Wholesale Prices, and Value of Production: 1929 to 1937 184 XIV Output Per Man and Per Hour, Manufacturing: 1929 to 1937 186 xx LIST OF TABLES TABLE PAGE XV Acquisition, Disposal, and Inventory of Surplus Property through March 31, 1946 190 XVI Storage of Major Groups of ASF Items: 31 July 1944 192 GRAPHIC PRESENTATION SIMPLIFIED AN EXPANDING ART I HE major development and utili- zation of graphic presentation as a medium for translating statistics into condensed visual form have taken place during the present century. Statistical charts were employed previously to a limited extent by specialists in various branches of science, but were little used in the world of commerce and industry. Much of the progress achieved in the last fifty years must be credited to the pioneers who visualized the potentialities of a wider employment of graphic presentation in these fields. Worthy of special mention is the work of Willard C. Brinton, whose Graphic Methods for Presenting Facts was published in 1914. In the following decade there appeared a number of excellent treatises on this subject, among them Karsten's Charts: How to Make and Use Them, and Riggleman's Graphic Methods for Presenting Business Statistics. Brinton's encyclopedic Graphic Presentation, containing prac- tically every known chart design, was one of the outstanding contribu- tions in the decade 1930-40. Time Series Charts, A Manual of I o cr x o 2 LU cr LU _J CD LU "I <x 00 CD 10 I I 5il U 00 (M 0(T> QJ 0)0) -3 LL U. U- t t tt o Z) Q O or o_ CO LU _l ID O LU X o CO o o o o o o 00 I I 05 1 fc K ? g 05 o o c Cvj AN EXPANDING ART 3 Design and Construction, prepared by the Committee on Standards for Graphic Presentation under the procedure of the American Standards Association, published in 1938, marked an important ad- vance in the standardization of nomenclature and methods of pres- entation. GRAPHIC PRESENTATION IN TWO WORLD WARS A comparison of the use of graphic methods by Army agencies during the last war with the extent they were employed to record and summarize military statistics in World War I gives some indication of the advances realized in this field during the last twenty -five years. For some time during World War I, the production of statistical charts was centered chiefly in the Statistics Branch of the General Staff. As a member of that agency, the writer had many opportunities to observe the methods employed in the various services for presenting statistical data. Of figures there was no end, but few attempts were made to reduce them to graphic form. Only a limited number of the higher officers were familiar with this type of presentation. In the General Staff the value of compact graphic summaries of the principal statistical facts of the war soon gained recognition. Early in 1918, the Statistics Branch established a system of weekly reports for circulation in the General Staff. These reports consisted of sta- tistical charts accompanied by text discussion and summaries. This service was supplemented by large display charts for presentation in weekly conferences attended by the Secretary of War, the Chief of Staff, and a selected group of officers representing the various services. Copies of two charts shown in these conferences appear on pages 2 and 4. Both have a certain historical interest. Chart 1 played a prominent part in the crisis which finally resulted in the removal of combat plane and engine procurement from the Signal Corps to an- other procurement agency. The curve chart shows the successive reduc- tions in the schedules of production from December, 1917, through February, 1918. The bars at the right indicate the effect of these reduc- tions, after allowing for transportation to Europe and other delays, on the projected supply of fighting planes available at the French front by the following July. Chart 2 pictures the shipping situation resulting from the submarine campaign against the British Merchant Marine from the beginning of GRAPHIC PRESENTATION SIMPLIFIED 90 QUARTERS 3 4 1914 CHART 2. BALANCE OF CONSTRUCTION AND SINKINGS, BRITISH MERCHANT MARINE: 1914 TO 1916. the war in 1914 to the end of 1916. The 100 percent line represents the total tonnage at the outbreak of war. The black portions of the curve indicate the new tonnage built, the shaded portions the tonnage sunk. The end of the curve in each quarter shows the net balance to that date. The subjects discussed in these conferences were limited to questions of major importance in the conduct of the war. Few of the officers attending them were accustomed to the use of charts as a medium for the presentation of statistical data. Some of them found rather puzzling the conversion of the tabular forms with which they were familiar to graphic arrangements of curves, bars, and columns. At the end of the first conference one of the officers, a lieutenant general, confessed that he had been able to understand only the bar charts and added the com- ment that the other types, particularly the curve designs, were too tech- nical. Experience quickly demonstrated the need for extreme simplicity in design and the organization of complicated presentations into independent units limited to single aspects of the subject-matter. Every effort was directed toward making each chart so clear that its meaning and significance could be grasped in the shortest possible time. Details which did not bear directly on the purpose of the chart were rigorously excluded. Verbal definitions and explanations AN EXPANDING ART 5 were reduced to a minimum by clear labeling of each element in the design. Within a few months after the declaration of war in 1941, facilities for the production of statistical charts were installed by every major procurement agency of the Army. Several months earlier, Colonel, later General, Leonard P. Ayres, who directed the work of the General Staff Statistics Branch in World War I, was called to active service to head the central statistical organization. The adoption of graphic methods in the various services was furthered by the active support of many officers from civil occupations, where their advantages were generally recognized. Early in the war, arrangements were made by General Ayres for monthly meetings with the House and Senate Military Committees for the presentation of current information concerning the procurement of supplies and military equipment. For this purpose large display charts in color were employed. The sessions were short, lasting usually from one to two hours. Only through the facility for condensation afforded by charts was it possible to cover in so short a time the required range of subjects and volume of data. Many knotty questions arising in the course of the discussions were quickly cleared up by charts which com- pressed on a few square yards of cardboard the pertinent facts from tables covering scores of pages. CHARTS VERSUS TABLES Charts are the shorthand of statistics. In a period in which every kind of factual information tends more and more to expression in statistical terms, they have become one of the most effective means for converting masses of data to a form that facilitates rapid comprehension and inter- pretation. Statistical information presented graphically has the great advantage over tables that it is more easily understood and remembered than the same data in tabular form. This applies particularly to inter- related factors, which in the chart form part of an integrated whole, while in the table they appear in unconnected detail. The coordination of significant relationships made apparent by the graphic method is of special value to executives whose duties leave them little time for analysis of data presented in tables. Charts serve better than any other method of presentation where data must be presented to a number of persons at the same time. Statistical tables cannot be used effectively in a conference, board meeting, or GRAPHIC PRESENTATION SIMPLIFIED hearing. The employment of display charts for such purposes has kept pace with the increasing use of the conference method for discussion and study of economic and legislative problems. IMPROVEMENTS IN EQUIPMENT Shortening of the training period has been made possible by innova- tions in equipment which have reduced the needier long practice and a high degree of manual skill. The introduction of two inventions, mechanical lettering guides and a new type of adhesive screen for the application of shading and color, has greatly simplified the drafting techniques employed in the production of statistical charts. Lettering of titles, scales, labels, and stubs usually takes from one half to two thirds of the time required to complete a chart. Before lettering guides came into common use, the proportion of time for this part of the work, done by hand, was much greater, while the results were inferior in uniformity and appearance to those obtainable with the guides. Free- hand lettering is seldom seen now except for ornamental lettering or on very large charts where the size of the lettering exceeds the capacity 25-R 97 56 80-R 26 47 19 77 24-R 20-R The Para-Tone Company FIGURE 1. SAMPLES OF ADHESIVE SCREENS. AN EXPANDING ART 7 of the guides. Relatively few statistical draftsmen can do good freehand lettering. In an extensive check of drafting rooms in Washington the average was less than 25 percent. The use of adhesive screens for shading and color has cut down ma- terially the time, labor, and skill required for filling in surfaces on statis- tical charts. Hatching by hand or with a section liner was a tiresome and time-consuming job, and the product often lacked uniformity in lining and spacing. In addition the patterns of shading that could be done by hand were limited in number and variety. A few samples of the many designs now available are shown in Figure 1. They are backed with a special adhesive which permits removal and replacement, if cor- rections or substitutions are necessary, without defacing the surface of the chart. They can be applied in about one tenth the time that would be needed to duplicate them by hand. Formerly, where color was employed, poster paints or water-colors were painted on the chart with a brush. The process was extremely slow as compared with the speed attainable with adhesive colors, and the results were less finished and attractive. The saving in time is around 60 to 75 percent. REDUCTION IN LENGTH OF TRAINING Today practically all large enterprises maintain graphic records of their internal operations. That the use of these methods has not spread to the same extent among the smaller business firms is partly due to the common assumption that the preparation of statistical charts requires the services of highly skilled draftsmen. The experience gained during the last war in the training of drafting apprentices does not bear out this assumption. On account of the heavy demands of the military agencies and the shortage of draftsmen, it became necessary to recruit drafting personnel from every possible source. In Washington alone a large num- ber of clerks, typists, and other clerical employees were enlisted for apprenticeship courses in drafting. Within a surprisingly short time most of them were able to turn out work of acceptable quality. Many of these recruits were women, with a sprinkling of young men who failed to pass the physical tests for the draft. Practically all ac- cepted willingly the opportunity to learn statistical drafting. With some the higher rate of pay was the chief incentive. Others welcomed the release from monotonous clerical duties offered by the new occupation. A creative activity that gives play to imagination, ingenuity, and the 8 GRAPHIC PRESENTATION SIMPLIFIED exercise of manual skill has attractions lacking in the average clerical job. An experiment conducted by a Federal agency in 1947, involving the use of partly trained drafting personnel, showed some interesting re- sults. The project was the establishment of a system of control charts in each of thirty-three regions throughout the country. Many difficulties were encountered. In some localities the services of trained draftsmen were unobtainable. In several instances it became necessary to send skilled personnel from Washington to get the projects started. The ex- perience was enlightening, particularly where, due to the shortage of draftsmen, it became necessary, in order to meet the emergency, to develop a drafting force recruited from office employees engaged in other occupations. On the whole, these makeshift methods were success- ful. Within the time limit set, a matter of two months, each of the regions was able to show the status of its operations in a series of fairly presentable charts. TRAINING METHODS Apprentice training during World War II was carried on chiefly in large drafting rooms under the direction of experienced supervisors and chief draftsmen. Beginners were first taught the use of a few drafting instruments. Following this, they were assigned simple tasks under close supervision on current jobs in process. Through the instruction they re- ceived from the chief draftsman and their observation of the* work per- formed by other members of the drafting staff, they gradually acquired a working knowledge of the use of scales, plotting methods, application of shading and color, and lettering with mechanical guides. The time required for development of average speed in lining, plotting, and let- tering generally ranged from one to three months. The conditions were those which usually exist where the volume of work is large enough to warrant specialization. The selection of designs usually was made by a member of the statistical staff in consultation with the supervisor. Details of the design and lay-out were sketched by the chief draftsman, who also wrote the instructions concerning the dimensions and spacing of the chart, what scales to use, the weight of the lines, the curve patterns, the color and shading, and the size and dis- tribution of the lettering. The draftsman had only to carry out these instructions. Any question or doubt arising in the course of the work was quickly resolved by consultation with the chief draftsman. AN EXPANDING ART 9 This method, which closely resembles those employed by industry in training beginners for specialized mechanical operations, has the advan- tage that it develops a fair degree of productive capacity in the shortest possible time. Its weakness, from the standpoint of the embryo drafts- man, is that it gives him little opportunity to acquire the general back- ground he will need if later he finds himself in a position where he must take the responsibility for the entire process, involving not only the manual execution of the chart, but the selection of the design and com- bination of the graphic elements to bring out clearly the purpose of the chart. The facilities afforded by ample equipment and skilled supervision found in the drafting installations of governmental agencies and large corporations are generally lacking in small commercial and industrial enterprises. Apprentice training of the type described in the preceding paragraphs is out of the question. The beginner can make a start by tak- ing a short course in drafting. The long study and practice required for mechanical or architectural drafting is unnecessary. However, the aver- age teacher of drafting knows little or nothing of graphic presentation. At the end of the course, the student will have acquired some profi- ciency in the use of drafting instruments, probably sufficient to enable him to carry on under conditions where the major part of the thinking and planning is done by others, but entirely inadequate if he is faced with the problems of selecting and adapting graphic designs to the requirements of complicated statistical presentations. The method of training suggested in later chapters of this volume was planned for those who must depend on their own efforts, without the aid of skilled supervision and instruction. It comprises a careful reading of Chapters II to XVI, in which are described the various graphic types commonly employed in statistical charts, the uses for which each is adapted, their limitations, and their relation to the many forms in which the results of statistical tabulation, research, and analysis are embodied. Included are detailed instructions in methods of lay-out and plotting, with examples -for practice on small charts with the tools immediately at hand, followed by suggestions and rules for planning and drafting charts of greater size and more complicated designs, involving the use of additional types of equip- ment. The principle is that of learning by doing. It will insure at least the acquisition of what so many draftsmen lack, a thorough understanding of the why as well as the how of each step of the process. CURVE CHARTS i HE curve chart, sometimes re- ferred to as a "line" chart, is one of the oldest forms of graphic pres- entation. It is most frequently used in presenting time series, in which the data correspond to successive time periods. The curve design is generally employed in charts showing projection of trends, or where exact plotting for close reading is required. It is not well suited for charts of short time series nor where the purpose of the chart is to show comparisons of size or amount rather than the move- ment and direction of change. DESIGNATION OF CHART COMPONENTS Chart 3 shows the terms generally employed for designating the vari- ous curve-chart components. Many of the terms apply also to other graphic types. These designations, with slight modifications, follow the terminology approved by the American Standards Association. A variation of minor importance is "stub," sometimes used to desig- 10 I CO II 12 GRAPHIC PRESENTATION SIMPLIFIED ORIGINAL SCALE ARRANGEMENT JAN CONTRACTING TIME SCALE APR JAN APR CONTRACTING TIME AND EXPANDING AMOUNT SCALE JAN APR EXPANDING TIME SCALE JAN APR EXPANDING AMOUNT SCALE JAN APR CONTRACTING AMOUNT SCALE JAN APR CONTRACTING AMOUNT AND EXPANDING TIME SCALE JAN APR CHART 4. EFFECTS OF SCALE ALTERATIONS. FROM Time Series Charts, A Manual of Design and Construction. CURVE CHARTS 13 nate the abbreviated scale rulings in time and amount scales, called in this example "ticks." "Stub" is confusing, for the reason that it applies also to the list of items in bar charts. Another term not shown is "grid," signifying the total plotting area, bounded by the side, top, and bottom lines of the chart. TITLES The title should be brief, but without sacrifice of clarity or omission of essential details. As to position, above or below the grid, the practice varies. In charts appearing in periodicals it is often placed below the drawing. Titles of display charts are generally lettered above the grid. If economy of space is important, as in miniature charts, the titles, if not too long and not accompanied by subtitles, may be lettered within the grid. If the chart is surrounded by a border, the title is centered between the vertical border lines, not over the space occupied by the chart. ABBREVIATIONS FOR TIME SCALES Time scales are in units of years, months, weeks, or days. Frequently in charts of yearly data there will not be room to letter the full figures, in which case two digits with an apostrophe may be substituted, as '39, '40. If there is enough space, three-letter abbreviations should be used for monthly time units. If this results in crowding, single-letter abbre- viations may be employed. Time-scale abbreviations are not followed by a period. Time units in weeks should be lettered in figures, with the month lettered horizontally below. The clearest form is 1-7, 8-14, and so on. Time units in days of the week should be designated by three- letter abbreviations. PROPORTIONS OF WIDTH AND HEIGHT The impression created by a curve chart depends to a great extent on the shape of the grid and the distribution of time and amount scales. Overexpansion or contraction of one of the scales throws the graphic picture out of balance and makes interpretation difficult. Chart 4 illus- trates the effects of different scale alterations. While no fixed rules for the proportions of grid dimensions can be laid down, a convenient standard is the method known as "root-two," a ratio of 1 (short side) to 1.414 (long side). These proportions approxi- 14 GRAPHIC PRESENTATION SIMPLIFIED mate those of standard sizes of paper and illustration board. The table of root-two dimensions on page 15 will save time and calculation of grid measurements. If for any reason either dimension is predetermined to fit a given space, the other dimension can be found immediately by reference to the table. These proportions are suggested as a general guide. Modifications will often be necessary if the shape of the chart has to be accommo- dated to space requirements of other material, as, for example, column widths in periodicals, reports, and other printed matter. SCALE NUMBERS Amount scales should be in even numbers or in multiples of five or ten. No definite rule can be laid down concerning the number of amount-scale rulings, but ordinarily they should not exceed five. POSITION AND LABELING OF SCALES The position of the amount scale is to the left of the grid, close to and exactly opposite the scale rulings. In wide charts covering a large number of plottings the scale may be repeated at the right of the grid. The amount-scale unit, if rounded, should be lettered under the title. It should specify not only the size of the unit, but what it represents, as "Millions of dollars," "Thousands of men," etc. If this is done, the cap- tion over the scale can be shortened to a single word, "Millions" or "Thousands," a considerable advantage in drafting, as space for scale captions is usually limited. Scale labels should not be lettered vertically at the left or right of the scale column. All lettering should be easily read without turning the chart sidewise. If monthly series extend over a year, the end of each year should be indicated by a heavier vertical rule or by the symbol | between December and January. Both methods are shown in 'Chart 3. SCALE RULINGS The number of scale rulings for time and amount scales depends on the nature and distribution of the data and the shape and dimensions of the grid. The extremes in practice range from too little to too much. Chart 5 shows an example of too much. The multiplicity of rules clut- CURVE CHARTS 15 TABLE I ROOT-TWO DIMENSIONS Short Long Short Long Short Long Short Long Short Long Short Long Side Side Side Side Side Side Side Side Side Side Side Side 1.0 1.4 4.5 6.4 8.0 11.3 11.5 16.3 15.0 21.2 18.5 26.1 1.1 1.6 4.6 6.5 8.1 11.5 11.6 16.4 15.1 21.4 18.6 26.3 1.2 1.7 4.7 6.7 8.2 11.6 11.7 16.5 15.2 21.5 18.7 26.5 1.3 1.8 4.8 6.8 8.3 11.7 11.8 16.7 15.3 21.6 18.8 26.6 1.4 2.0 4.9 6.9 8.4 11.9 11.9 16.8 15.4 21.8 18.9 26.7 1.5 2.1 5.0 7.1 8.5 12.0 12.0 17.0 15.5 21.9 19.0 26.9 1.6 2.3 5.1 7.2 8.6 12.2 12.1 17.1 15.6 22.0 19.1 27.0 1.7 2.4 5.2 7.4 8.7 12.3 12.2 17.3 15.7 22.2 19.2 27.1 1.8 2.6 5.3 7.5 8.8 12.4 12.3 17.4 15.8 22.4 19.3 27.3 1.9 2.7 5.4 7.6 8.9 12.6 12.4 17.5 15.9 22.5 19.4 27.5 2.0 2.8 5.5 7.8 9.0 12.7 12.5 17.7 16.0 22.6 19.5 27.6 2.1 3.0 5.6 7.9 9.1 12.9 12.6 17.8 16.1 22.7 19.6 27.7 2.2 3.1 5.7 8.1 9.2 13.0 12.7 17.9 16.2 22.9 19.7 27.9 2.3 3.2 5.8 8.2 9.3 13.2 12.8 18.1 16.3 23.0 19.8 28.0 2.4 3.4 5.9 8.3 9.4 13.3 12.9 18.2 16.4 23.2 19.9 28.1 2.5 3.5 6.0 8.5 9.5 13.4 13.0 18.4 16.5 23.3 20.0 28.3 2.6 3.7 6.1 8.6 9.6 13.5 13.1 18.5 16.6 23.5 20.1 28.4 2.7 3.8 6.2 8.8 9.7 13.7 13.2 18.7 16.7 23.6 20.2 28.5 2.8 4.0 6.3 8.9 9.8 13.9 13.3 18.8 16.8 23.7 20.3 28.6 2.9 4.1 6.4 9.1 9.9 14.0 13.4 18.9 16.9 23.9 20.4 28.8 3.0 4.2 6.5 9.2 10.0 14.1 13.5 19.1 17.0 24.0 20.5 29.0 3.1 4.4 6.6 9.3 10.1 14.3 13.6 19.2 17.1 24.1 20.6 29.1 3.2 4.5 6.7 9.5 10.2 14.4 13.7 19.4 17.2 24.3 20.7 29.3 3.3 4.7 6.8 9.6 10.3 14.6 13.8 19.6 17.3 24.5 20.8 29.5 3.4 4.8 6.9 9.8 10.4 14.7 13.9 19.8 17.4 24.6 20.9 29.6 3.5 4.9 7.0 9.9 10.5 14.8 14.0 19.9 17.5 24.7 21.0 29.7 3.6 5.1 7.1 10.0 10.6 15.0 14.1 20.0 17.6 24.9 21.1 29.9 3.7 5.2 7.2 10.2 10.7 15.1 14.2 20.1 17.7 25.0 21.2 30.0 3.8 5.4 7.3 10.3 10.8 15.3 14.3 20.2 17.8 25.2 21.3 30.1 3.9 5.5 7.4 10.5 10.9 15.4 14.4 20.4 17.9 25.3 21.4 30.2 4.0 5.7 7.5 10.6 11.0 15.6 14.5 20.5 18.0 25.5 21.5 30.4 4.1 5.8 7.6 10.8 11.1 15.7 14.6 20.6 18.1 25.6 21.6 30.5 4.2 5.9 7.7 10.9 11.2 15.8 14.7 20.7 18.2 25.7 21.7 30.6 4.3 6.1 7.8 11.0 11.3 16.0 14.8 20.9 18.3 25.9 21.8 30.8 4.4 6.2 7.9 11.2 11.4 16.1 14.9 21.0 18.4 26.0 21.9 31.0 16 GRAPHIC PRESENTATION SIMPLIFIED CHART 5. Too MUCH RULING. THOUSAND THOUS AND 00 80 60 40 20 * . 60 40 20 ; ^^ ^/ f J \j /\ /I V r\ [ y X ^ 7 j J F M A M J JASONDJ F M A M J 1946 1947 CHART 6. RULING RE- PLACED BY TICKS. THOUSAND 1100 80 60 40 20 | | | | | | | I I I I I I I I I I In JFMAMJJASONDJFMAMJ 1946 1947 THOUSAND 100 80 40 20 CHART?. COMBINA- TION OF TICKS AND RULING. I 1 J I I J F M A MJ JASONDJ F M A M J 20 CURVE CHARTS 17 ters up the chart unnecessarily and obstructs rather than facilitates reading the curve. Chart 6 shows the same curve on a grid in which the vertical and horizontal rulings are replaced by ticks. Those who favor this method hold that all ruling extending through the field of the grid detracts from the graphic effect of the curve. Against this view is the objection that the curves appear suspended in the air, separated from the scales so far that only a rough approximation of the amount value of any given plotting point can be made. The same difficulty is encountered in iden- tifying a point in the curve with the corresponding time unit below it. A compromise which has the sanction of generally accepted practice is shown in Chart 7. The ruling for the time scale is inserted at quar- terly periods, with the intervening months indicated by ticks. The amount scale is ruled at intervals of twenty, with ticks representing units of five. The grid field is fairly clear, and the identification of any point in the curve with the corresponding amount or date presents little difficulty. CURVE PATTERNS Chart 8 shows some of the types of curve patterns that are in com- mon use. The simpler designs are more economical from the point of view of the time consumed in the drafting and are generally the most effective, particularly in charts where the curves are close together. If the number of curves does not exceed three, marked contrast in the CHART 8. CURVE PATTERNS. 18 GRAPHIC PRESENTATION SIMPLIFIED patterns selected is unnecessary. The usual practice is to employ a solid curve for the most important item, a dash curve for the next in order of importance, and dots for the third. Although somewhat less striking, different weights of solid curves may be used. On large display charts the curves may be fashioned of narrow strips of color. The strips are cut from the adhesive color sheets and pasted on the illustration board to form the line of the curve. Irregular curves should be lighter than smooth ones. Usually one of the curves in multicurve charts is of special signifi- cance. This should be plotted in a pattern that will stand out clearly from the others. For this purpose the line-and-dot and the ball-and- line types are very effective. OMISSION OF ZERO BASE An important rule in the drafting of curve charts is that the amount scale should begin at zero. In comparisons of size the omission of the zero base, unless clearly indicated, is likely to give a misleading impres- sion of the relative values and trend. The first chart on the opposite page shows the data plotted on a grid covering the full amount scale. In the second the amount scale under the lowest point of the curve is omitted. The third represents the generally approved method for indi- cating the omission of the zero base. Another form commonly used con- sists merely of a wavy line similar to the one at the bottom of the plotting field in the third chart. A light straight line with wavy sections at each end is sometimes used for this purpose. Whatever the device, it should clearly remind the observer that the full scale is not shown. Whether to include the full scale or omit part of it depends on the nature of the data. Fluctuations in the curve may occur within a lim- ited range only. Changes in prices of bonds are an example. Against the par value of $100, the price variation within a normal year may amount to only a few dollars. These small changes are important to investors, but if the whole scale from zero to 100 is included, they will be scarcely visible in the curve. 100 PERCENT BASE IN INDEX-NUMBER CHARTS Exceptions to the zero-base rule are admissible in index-number curve charts, where the relation of the curves is to 100 rather than zero. The usual practice is to omit the zero base in such charts without the CURVE CHARTS 19 600 500 400 200 100 HEAVY TANKS ACCEPTED 1941 600 500 400 300 200 HEAVY TANKS ACCEPTED / / 1941 /r ^. ^ ' \ / ) V y ' JFMA. MJJASOND JFMAMJJA50NO 600 500 400 300 200 HEAVY TANKS ACCEPTED JFMAMJJASONO CHART 9. OMISSION OF ZERO BASE. FROM Manual of Statistics, WAR DEPARTMENT, SOS. 20 GRAPHIC PRESENTATION SIMPLIFIED reminder of a break in the scale. Instead, the 100 percent line is made heavier than the other horizontal lines, as illustrated in Chart 10, to indicate that the curves are to be interpreted with relation to this base. A further reason for omitting the lower part of the amount scale in this chart was to gain space for the curve plotting. Had the full scale WAGES, PRICES, AND PRODUCTION MANUFACTURING INDUSTRY, 1935. 1936, 1937 INDEX NUMBERS, MONTHLY AVERAGE 1935 '100 National Industrial Conference Board CHART 10. CURVE CHARTS 21 been included, the curves would have been brought too close together for easy reading and comparison. The number of curves that can be shown effectively in a single chart, if they are very irregular or cross each other, is generally limited to three or at most four. But if the scale outside the plotting field is omitted, thereby increasing the separation between the curves, a fairly clear presentation of a larger number is possible. BREAK IN TIME SCALE Sometimes monthly time series start from a date several years subse- quent to the period with which they are compared. In such cases lack of space may make it advisable to omit part of the intervening time units. In Chart 11 index numbers of retail prices for fruits and vegeta- bles and for all foods during the last two war years are compared with the monthly average in 1939. To have included all the monthly data 200 180 J40 AVERAGE JFMAMJJASONDJFMAMJJASOND 120 100 80 CHART 11. RETAIL COST OF FOOD: 1939, 1944, AND 1945. 22 GRAPHIC PRESENTATION SIMPLIFIED for the intervening four years would have made the chart too crowded. The monthly average in 1939 is connected with the plotting for the first month in 1944 by dash lines crossing the break in the time scale. If there is a gap in a series for the reason that the data are not avail- able, a break in the curve is necessary. The usual practice is to fill in the break with a light dotted line labeled "Data not available," or it may be footnoted, in which case the footnote symbol should be placed closely above or below the dotted line. FITTING CURVES TO GAIN SPACE When it is necessary to present a large number of series on one chart the curves may be "fitted" by the method illustrated in Chart 12. This method is feasible where the curves represent index-number series in which the base for all of them is the same. This is indicated in the example by the figure 100 at the first plotting point of each series. The spaces between the horizontal rulings are equal to ten points of the index. This chart was reduced from an original printed on a standard 8/2-by- 1 1-inch sheet. Twelve series were fitted within this space. If drafted separately, each with its individual amount scale, they would have required many times the space, without the advantage of close com- parison secured by this method. Another feature of interest in this chart is the combination of yearly and monthly plotting. For the first six years the ball-and-line pattern is used for the yearly averages. This is continued through the following years, but with the addition of monthly data plotted in light dash curves. In this manner the monthly record is kept up to date until the end of the year, when the twelve-month average is added. Lettering the last figure at the end of the curve aids in showing the exact current status, which often is the point of chief interest to the observer. It is of special advantage to those who customarily think in terms of figures or who do not readily interpret charted statisti- cal data. In nearly all curve charts that picture extensive economic series it is advisable to label the high, the low, and the end points of the curve. Lettering of titles following the course of each curve is imposed in this chart by the close fitting. If there is sufficient space, titles should CURVE CHARTS DEPRESSION, RECOVERY, DEPRESSION UNITED STATES, 1929-1933 23 INDEX NUMBERS, I929-IOO 93- 1935 1936 1937 1938 National Industrial Conference Board CHART 12. be lettered horizontally. If title and curve are widely separated, a connecting arrow should be drawn between them. OMISSION OF TIME-SCALE RULING ABOVE CURVES In single-curve charts the time-scale ruling above the curve is often omitted. The employment of this method in charts containing a number 24 GRAPHIC PRESENTATION SIMPLIFIED of curves of approximately equal significance, as illustrated in Chart 13 is sometimes criticized on the ground that the lack of ruling in the upper part of the chart tends to emphasize the importance of the high- est curve. Millions SO Type C V sf' Type D CHART 13. STOCKS OF C, D, AND K EMERGENCY RATIONS: 1943 (MILLIONS OF RATIONS). FROM Statistical Handbook, QUARTERMASTER CORPS. PLOTTING POINTS The data may be plotted on the vertical time-scale lines or centered in the spaces between them. Plotting to the line is generally preferred. The observer tends to read a curve where it crosses a line. Also, in plot-to-space charts ruled at wide intervals it is difficult to identify the plotting with the corresponding time unit at points where the angle of the curve does not change. Plot-to-space should be used if the series contains differing time units (such as end of the month and middle of the month) or if the data are reported at irregular intervals. Chart 14 shows both methods. The plot-to-space chart is ruled in quarterly subdivisions. The plot-to-line chart, having only eleven spaces, cannot be subdivided in this manner, as one of the quarters will be narrower than the other three. Plot-to-space must be used if quarterly or semiannual subdivisions are to be shown. CURVE CHARTS 25 100 80 60 40 20 till PLOTTED -TO- SPACE A \ J F MAMJ JASOND 100 80 GO 40 20 I I I I PLOTTED- TO-LINE J F MAMJ JASOND CHART 14. PLOTTING TO SPACE OR LINE. 26 GRAPHIC PRESENTATION SIMPLIFIED MOVING-AVERAGE CURVES In Chart 15 the dash line represents a moving average of the monthly data. Moving-average curves are frequently added to indicate the approximate general trend, which is otherwise difficult to determine because of the irregular individual plottings. The solid curve in this chart shows the number of failures by months. The dash curve is the average, at successive entries, of the last twelve months. This average was recomputed each month by dropping the amount for the first month of the preceding twelve-month average and adding the data for the current month. 1200 1000 800 600 400 200 BUSINESS FAILURES 1941 1942 1943 1944 1945 1946 1947 Cleveland Trust Company Business Bulletin CHART 15. CURVE CHARTS 27 Chart 16 shows another type of moving average, sometimes called a "progressive average," in which the additional curve represents an average of all the values to the date of each plotting. The amount for each year is averaged with all of the preceding entries. The lower curve represents an average of the placements to the current date. MILLIONS MILLIONS 15 12 Yearly Placements I I 1 I 15 12 1937 1938 1939 I94O 1941 1942 1943 1944 1945 CHART 16. PLACEMENTS BY U.S. EMPLOYMENT SERVICE: 1937 TO 1945. WEIGHT OF GRID LINES The grid lines should be lighter than the curves, with the base line somewhat heavier than the others. All vertical lines should be of equal weight, unless the time scale is subdivided in quarters or other time periods, indicated by heavier rules. Very wide base lines, sometimes employed for pictorial effect, distort the graphic impression by making the base line the most prominent feature of the chart. 28 GRAPHIC PRESENTATION SIMPLIFIED BROKEN CURVE If one curve in a chart of two or more contains a fluctuation so extreme that if plotted to scale it would dwarf the changes in the others, the curve may be broken as shown in Chart 17. When this is done, the point to which the curve would extend if shown in full should be lettered at the place where the break is made. 10 CHART 17. BROKEN CURVE. STOCK-PRICE CHARTS A curve type employed for recording the movement of stock prices is shown in Chart 18. The range of prices is indicated by heavy vertical lines at the various plotting points, extending from the highest to the lowest price at which the stock was sold. The intersecting curve shows the closing price for the day. Many stock charts include a column chart showing the volume of sales, placed below the price chart. CUMULATIVE-CURVE CHARTS The cumulative-curve type, which is illustrated in Chart 19, is used when the purpose is to show over-all results through an extended period of time. Each plotting represents the sum of all the entries up to date. CURVE CHARTS 29 40 38 36 34 32 30 28 26 24 22 20 CLOSING PRICE DAYS MONTH DAYS MONTH CHART 18. STOCK-PRICE CHART. TITLE X LABEL -.--*' LABEL B TIME CHART 19. CUMULATIVE-CURVE CHART. 30 MULTIPLE-SCALE CHARTS GRAPHIC PRESENTATION SIMPLIFIED The use of two or more amount scales for comparisons of series in which the units are unlike and, therefore, not comparable for example, total wages paid compared with number of wage-earners, physical vol- ume of production with total value of production, prices compared with total sales generally results in an ineffective and confusing pres- entation which is difficult to understand and to interpret. Comparisons of this nature can be much more clearly shown by reducing the com- ponents to a comparable basis as percentages or index numbers. MULTIPLE-TIME-SCALE CHARTS This type, which is illustrated in Chart 20, is employed frequently for comparisons of monthly data by years. The time scale, in months, is lettered below the grid. The curves represent the years included in the comparison. TITLE TIME CHART 20. MULTIPLE-TIME-SCALE CHART. STAIRCASE-CURVE CHARTS The staircase-curve designation is applied to a type in which hori- zontal and vertical lines are substituted for slope curves. Chart 21 is an example. The employment of this form of curve is generally limited to CURVE CHARTS 31 charts of a single series. With two or more series the vertical lines of the curves frequently overlap. Bii: 20 15 10 5 .Ions APPROPRIATIONS i | 1940 19 41 : 1 _: 1917 r ; 1918 .. rr ....J " I , , JFMAMJJASONDJFMAMJJASOND CHART 21. WAR APPROPRIATIONS: 1917-18 AND 1940-41. FROM Manual of Statistics, WAR DEPARTMENT, SOS. KEYS Keys for the identification of the curves in multicurve charts are seldom used or needed. Usually there is room to label the curves indi- vidually, without recourse to the key method of identification. The character and meaning of each curve should be instantly apparent. The use of keys hinders unnecessarily rapid reading and interpreta- tion of the chart. SURFACE-CURVE CHARTS charts can be dressed up by filling in the space between curves with shading or color. If adhesive patterns are used, the extra work required is insignificant in proportion to the improvement in appearance and effectiveness. DIFFERENTIATION OF TRENDS BY SHADING In Chart 22 the curves are supplemented with two patterns of shad- ing. The dotted area extends from the high level reached in 1937 to the lowest point of the downward trend. The following recovery move- ment, outlined by the curves, is filled in with diagonal shading. The original from which this chart was copied is in color, red denoting depression and blue recovery. A feature worth noting in this design is the economy of space gained by placing the titles within the grids. Another is the lettering of index figures at the points of greatest interest, which in this case are the turn of the trend and extent of recovery to the last date of the series. 32 SURFACE. CURVE CHARTS 33 DEPRESSION AND RECOVERY UNITED STATES, 1937-1938 DEX NUMBERS, HIGH MONTH OF 1937-100 DEBITS TO INDIVIDUAL ACCOUNTS (OUTSIOf NEW YORK CITY) I , , I , National Industrial Conference Board CHART 22. STRATA CHARTS The combination of surface with curves is especially effective in multicurve charts of the type shown in Chart 23, sometimes called 34 GRAPHIC PRESENTATION SIMPLIFIED "strata" or "band" charts. The width of each band represents the size of the amounts measured from the total of the amount plotted below it. The total curve is made heavier than the curves of the subdivi- sions. THOUSANDS 1200 1000 800 600 400 2OO 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 CHART 23. PRODUCTION OF MOTOR TRUCKS AND TRUCK TRACTORS: 1936 TO 1945. DISTORTION PRODUCED BY STEEP CURVES If a chart contains a number of series which vary widely in individ- ual magnitude, optical distortion may result from the necessarily sharp changes in the angle of the curves. The space between steeply rising or falling curves always appears narrower than the vertical distance between the plotting points. This effect is illustrated in Chart 24, in which the vertical separation of the curves is the same at each plotting point. If the chart includes a number of series, the distortion may be increased by the cumulative irregularity of the curves. SURFACE. CURVE CHARTS 35 CHART 24. DISTORTION PRODUCED BY STEEP CURVES RISING OR FALLING AT A UNIFORM RATE. 36 GRAPHIC PRESENTATION SIMPLIFIED USE OF SHADING TO SHOW NET RESULTS Chart 25 illustrates the use of shading to show net differences in trends. The data consist of two series of index numbers covering the period 1939 to 1945, based on 1939 as 100. The upper curve represents an index of average weekly earnings of wage-earners in manufacturing, the lower a consumers' price index of commodities and services bought by families of wage-earners and moderate-income workers in large cities. The net gain in real earnings, after deducting the rise in prices, is indicated by filling in the space between the upper and lower curves with shading. 200 180 160 1940 1941 1942 1943 1944 1945 CHART 25. AVERAGE WEEKLY EARNINGS OF WAGE-EARNERS IN MANUFAC- TURING, AND CONSUMERS* PRICE INDEX: 1939 TO 1945. SHADING SIGNIFICANT TIME PERIODS Shading is sometimes employed to call attention to those periods in the time scale which are of special interest or importance. Two patterns of shading are used for this purpose in Chart 26, in which the curve represents the amount of money in circulation per capita in each year SURFACE. CURVE CHARTS DOLLARS 200 180 80 60 40 20 40 20 1916 '17 '18 '19 '20 '21 '22 '23 '24 '25 '26 '27 '28 '29 '30 '31 '32 '33 '34 '35 '36 '37 '38 '39 '40 '41 '42 '43 '44 '45 CHART 26. MONEY IN CIRCULATION, UNITED STATES, PER CAPITA: 1916 TO 1945. 38 GRAPHIC PRESENTATION SIMPLIFIED from 1916 to 1945. The figures for the end years of the two wars and the high and low of the intervening period are lettered below the curve. CONTRASTING NET CHANGES Different shadings or colors can be employed to contrast net changes where trends cross. The solid curve in Chart 27 represents the number of immigrant aliens admitted in the United States from 1932 to 1945. The departures over the same period are shown by the dash curve. The excess of departures over admissions, or net departures, is indicated by dotted shading. In 1936 the departures and admissions were approxi- mately equal. The cross-hatched area shows the volume of net admis- sions from that year on. THOUSANDS 100 ft 20 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 CHART 27. IMMIGRANT ALIENS ADMITTED AND DEPARTED: 1932 TO 1945. MINIATURE SURFACE-CURVE CHARTS Designs of the type illustrated in Chart 28, which involve the com- bination in a single chart of a considerable number of time-series SURFACE. CURVE CHARTS 39 CHART 28. TONNAGE RECEIVED AND SHIPPED BY QMC DEPOTS: 1944 (THOUSANDS OF TONS). FROM Statistical Yearbook, QUARTERMASTER CORPS. 40 GRAPHIC PRESENTATION SIMPLIFIED miniatures, present somewhat difficult problems in arrangement and lay-out. Of these, the most complicated are the space adjustments that are necessary to make all of the columns the same height and provide for equal spacing between the miniatures while at the same time ad- hering to a uniform plotting scale. The chart shows the movement of supplies in twenty-two quartermaster depots during the year 1944. The dotted and diagonal shadings represent receipts and shipments respec- tively. LONG-RANGE BUSINESS-ACTIVITY CHARTS The design shown in Chart 29, "American Business Activity," is frequently employed for picturing economic movements over an ex- tended period of time. The base is a computed normal, designated by the abbreviation "Nor." The curve shows the deviations, in percents, above or below this level. This type is one of the most effective in presentations of data related to some central point, standard, or level, such as over or below an average, above or under 100 percent, in excess of or less than an esti- mate or forecast, above or below a given year. 1940 1942 1944 1946 Cleveland Trust Company Business Bulletin CHART 29. SURFACE. CURVE CHARTS 41 EMPLOYMENT AND UNEMPLOYMENT UNITED STATES, 1929-1939 EMPLOYMENT BY GROUPS 1929 '30 '31 '32 '33 '34 '35 '36 '37 '38 '39 AVERAGE ONTHLY National Industrial Conference Board CHART 30. SHADED STAIRCASE-CURVE CHARTS Chart 30 is an example of the use of shading in a staircase-curve design. It presents a large volume of information, compressed by in- genious designing into a small amount of space. Nearly all the lettering is within the plotting field. Two time scales at the bottom of the page are made to serve for all ten charts. 42 GRAPHIC PRESENTATION SIMPLIFIED SHADING VERSUS SOLID BLACK Chart 31 pictures the fluctuation in aerial activity on the French front during World War I. The use of solid black makes it difficult to identify points in the curve with the corresponding units in the time scale. Light transparent shading is preferable to black for charts in which, as occurs in this example, the variation is extremely wide. 8,000 2,000 1,000 1918 1919 CHART 31. HOURS SPENT IN THE AIR BY AMERICAN SERVICE PLANES AT THE FRENCH FRONT DURING WORLD WAR I. FROM The War with Ger- many, BY LEONARD P. AYRES. SURFACE. CURVE CHARTS 43 ECONOMY OF SPACE IN DESIGN Two measures of increase in volume of production in the United States, total and per capita of population, are shown in Chart 32. Effec- tive presentation of a number of charts in limited space is favored by the elimination of all scales and ruling not absolutely necessary, with labels lettered as closely as possible to the curves. If the curves repre- sent marked growth or increase, a single right-hand amount scale is sufficient. VOLUME OF PRODUCTION UNITED STATES, 1859-1934 INDEX NUMBERS. BASE. 1899.100 -1 400 1859 '69 '79 '89 18991909 '19 '29'M 1859 '69 '79 '89 18991909 '9 2934 MANUFACTURING MINING AGRICULTURE GENERAL CMANUFACTURING, MINING , AND AGRICULTURE COMBINED) National Industrial Conference Board CHART 32. IV RATE-OF-CHANGE CHARTS THER terms employed to des- ignate rate-of -change charts are "ratio," "logarithmic," and "semi-loga- rithmic." "Ratio" and "rate-of-change" are most commonly used. The latter has at least the advantage that it is clearly descriptive of what this design purports to show. GRID RULING Arithmetic and rate-of-change scale rulings are compared in Chart 33. The spaces between the scale rulings in the arithmetic scale are equal. The corresponding spaces in the rate-of-change scale decrease in width with each successive ruling. The second chart shows an example of a three-cycle rate-of-change grid. The amount scale of the first cycle is 10 to 100; the second, 100 to 1,000; and the third, 1,000 to 10,000. If a fourth cycle were required, the scale would be 10,000 to 100,000, and if a fifth, 100,000 to 1,000,000. In multicycle charts the amount scale in each succeeding cycle is ten 44 RATE-OF- CHANGE CHARTS 45 ARITH- METIC 100 RATE OF CHANGE x X x X X <b" ' / 10 THREE-CYCLE GRID SCALE 10,000 F 1,000 100 10 CHART 33. ARITHMETIC AND RATE-OF-CHANGE SCALES. 46 GRAPHIC PRESENTATION SIMPLIFIED times the scale in the next cycle below it. The number of cycles re- quired depends on the size of the component figures. As the rate-of- change design has no zero base, the bottom line is not, as in arithmetic charts, made heavier than the other lines of the grid. OMISSION OF SCALE RULINGS If space for the chart is limited, any part of the scale above or below the curve may be omitted. In Chart 34 the series covers a range of 400 to 748. The scale begins at 400 and ends at 800. To have included in the scale the full cycle from 100 to 1,000 would have made the chart over three times larger. 400 CHART 34. TOP AND BOTTOM OF CYCLE OMITTED. RATE-OF-CHANGE CHARTS 47 RATE-OF-CHANGE VERSUS INDEX NUMBERS In Chart 35 the rate-of-change method for picturing rates of increase is compared with index numbers. The series represent the populations of Puerto Rico and Hawaii in the census years 1930 and 1940, with estimates by the Census Bureau for the intervening period. Reduced to thousands, the figures for Puerto Rico were 1,552 in 1930 and 1,877 in 1940, and for Hawaii 368 and 426 in the same years. The first chart shows the data plotted on a rate-of-change grid. The difference in the slope of the curves is so slight that it is not clear which represents the higher rate of growth. The wide separation of the curves increases the difficulty of the comparison. The second chart shows the two series converted to index numbers, the base, 100, representing th,? population in 1930. In this foSrTi the comparison is much clearer and more easily understood. It shows not only which had the higher rate in growth of population, but also facili- tates close reading of the difference in rates of increase. THOUSANDS 2000 1600 1200 1000 800 600 400 300 -RATE-OF-CHANGE - Puerto Rico Hawaii 125 120 115 no 105 100 INDE) < NUM 3ERS / Puert o Rico / / / f / f f Haw iii / 1 \ 1 1 1930 1932 1934 1936 1938 1940 1930 1932 1934 1936 1938 1940 CHART 35. GROWTH OF POPULATION, PUERTO Rico AND HAWAII: 1930 TO 1940. 48 GRAPHIC PRESENTATION SIMPLIFIED METHODS FOR LAYING OUT GRIDS A simple method for laying out the grids for small rate-of-change charts is illustrated in Chart 36. After determining the vertical dimen- sion of the grid, secure a sheet of printed logarithmic paper on which the cycles are somewhat larger than this dimension. Place the printed cycle diagonally across the allotted vertical space and note the points for the ruling. If the series extends into numbers requiring more than one cycle, the others will duplicate the ruling of the first one. Grids up to six inches in height can be laid out from the scale in Chart 37. A piece of paper the length of the vertical dimension is placed over the scale and moved to the left until the same dimension is reached. The lines of the scale indicate the plotting points for the grid. Grids of display size can be laid out by extending the lines in Chart 37 on a larger sheet of paper. CHART 36. METHOD FOR LAYING OUT RATE-OF-CHANGE GRIDS WITH LOGARITHMIC PAPER. EXPLANATORY NOTE To a great many persons the difference between arithmetic and loga- RATE-OF-CHANGE CHARTS 49 CHART 37. SCALE FOR LAYING our RATE-OF-CHANGE GRIDS. 50 GRAPHIC PRESENTATION SIMPLIFIED rithmic scale rulings is puzzling and confusing, particularly where both types appear in the same chart. In order to prevent any possibility of misunderstanding it is advisable to include in rate-of-change charts a note, preferably lettered within the grid, that will inform the reader that the relation between plotting points represents ratios of change, increase or decrease, rather than differences in size or amounts. A form sometimes used for this purpose in charts of this type is: "The scale focuses attention on rate of increase," or "decline," "loss," "growth," or "change." UNITS VARYING IN SIZE AND KIND Multicurve rate-of-change charts do not require the reduction of units of a different nature to a comparable basis. Chart 38 presents an example in which rates of increase of such diverse measures as miles of railway and telegraph and telephone wire, number of motor vehicles produced, value of radio apparatus, and production of airplanes are compared in the same chart. The unit quantities are adapted to the scale, which extends only to 10,000, although the actual totals of the basic units, with the exception of airplanes, all exceed this number. The units for railways and motor-vehicle production are in thousands; for radio apparatus, $100,000 value of production; and for telephones, 10,000 miles of wire. LIMITED USE OF RATE-OF-CHANGE DESIGNS Notwithstanding the many efforts that have been made to popularize this method of graphic presentation, rate-of-change designs are seldom employed in statistical charts relating to business, industrial, and re- lated activities. The position taken by the statistical authorities in the procurement agencies of the Army during the last war typifies the pre- vailing attitude concerning the use of this graphic type. Standards of Presentation, issued by the Statistics Branch, Control Division, Army Service Forces, for the guidance of its staff in the preparation of statis- tical reports, contains the following suggestive comment on the use of logarithmic charts: "There are two dangers in using a log-scale chart: ( 1 ) that it will be used improperly, and ( 2 ) that it will be misread even if properly used. Therefore, although extremely valuable under appropriate conditions, this type is recommended only when the picture cannot be shown RATE-OF-CHANGE CHARTS 51 INDUSTRIAL CONTRIBUTIONS OF SCIENCE AND INVENTION UNITED STATES, 1830-1930 00,000 MILES Or WIRE) RATE-OF-CHANGE CHART THE RATIO SCALE USED HERE FOCUSES ATTENTION UPON RATE OF GROWTH. THE UNIT FOR EACH CURVE IS INDICATED IN PARENTHESES. RAILWAYS 0,000 MILES OPERATED) MOTOR VEHICLE PRODUCT ON [1.000) 160 I860 1870 I860 1890 1900 1910 192.0 1930 National Industrial Conference Board CHART 38. 52 GRAPHIC PRESENTATION SIMPLIFIED ARITHMETIC SCALE AMOUNT 100 LOGARITHMIC SCALE AMOUNT 100 J J F INDEX LOG. SCALE 30% RATE OF / INCREASE / CHART 39. ARITHMETIC, LOGARITHMIC, AND INDEX LOG CHARTS. FROM Standards of Presentation, ARMY SERVICE FORCES. satisfactorily by some other means, such as conventional percentage measurement." These recommendations were followed by a graphic comparison of three methods, arithmetic, logarithmic, and index logarithmic, which is reproduced in Chart 39. The real test of these different methods is the impression the observer RATE-OF-CHANGE CHARTS 53 gets from them. Viewing Chart A alone, he would probably conclude that the rate of increase in Curve 1 is greater than in Curve 2. Chart B shows which series increased at the faster rate, but affords no means for determining quickly by inspection the difference in the rates of in- crease. The comparison in Chart C is much clearer, with the advantage that the rates for both curves can be easily read from the scale. The light dash percentage-of-increase lines aid in reading the rates, but their inclusion in charts of more than two series is inadvisable, as the multiplicity of lines is likely to be confusing. ,v BAR CHARTS HE term "bar charts" as used here applies to horizontal-bar charts. Vertical-bar charts, commonly designated "column charts," are discussed in another chapter. The bar type is one of the most frequently employed in graphic pres- entation and has many advantages. It is readily understood, even by those unaccustomed to reading charts, or who are not chart-minded. When the problem is one of comparing a large number of items, it is the only form that can be used effectively. It also possesses the out- standing advantage that it is one of the simplest and easiest to make. WIDE RANGE OF VALUES Chart 40 illustrates a problem frequently met with in the drafting of bar charts. The amount represented by the upper bar, Minneapolis, is nearly twice the next in size and around thirty times larger than the last item of the series. In order to gain space for the smaller bars of the series, the largest bar is broken. 54 BAR CHARTS 55 MINNEAPOLIS DULUTH KANSAS CITY ST. LOUIS CHICAGO OMAHA WICHITA PEORIA INDIANAPOLIS ST. JOSEPH MILWAUKEE SIOUX CITY CHART 40. RECEIPTS OF WHEAT AT PRIMARY MARKETS: 1943 (MILLIONS OF BUSHELS). LETTERING VERSUS SCALES There is some difference of opinion among statisticians concerning methods for indicating the values in bar and column charts. Against the 56 GRAPHIC PRESENTATION SIMPLIFIED practice of lettering the figures on the bars, it is argued that the letter- ing interferes with the graphic comparison, and where placed at the end of the bars, adds to their length, thereby distorting the impression of relative values. Those who object to lettering the figures in this man- ner prefer the use of a scale placed over the upper bar. This method is illustrated in Chart 41. The real test of any method is how it functions in practical use and how far it meets the special needs of the person or persons for whom the chart is made. Assume, for illustration, that a display chart contain- ing the data on criminal offenses drafted in Chart 41 is prepared for a hearing composed of Congressmen, lawyers, and enforcement officers. They are not likely to know much about graphics, and generally they think of statistics in terms of numbers. Also, the facts presented in the chart involve matters requiring legislative or other remedial action, for which the actual figures are likely to be essential. Assume further, as an example of the type of difficulty often encoun- tered in the use of scaled charts, that in the course of the hearing some- one questions the accuracy of the high rate for aggravated assault in 50 100 150 200 250 South Atlantic East South Central Pacific West South Central East North Central UNITED STATES Mountain Middle Atlantic CHART 41. CRIME RATES IN URBAN COMMUNITIES (PER 100,000 POPU- LATION), BY GEOGRAPHIC DIVISIONS: 1943 (DATA SCALED). BAR CHARTS 57 the South Atlantic division, which greatly exceeds the rates for this offense in all the other divisions, and demands the exact data. Measured from the scale, the segment extends from a little beyond 50 to about half-way between 200 and 250. An estimate by the ordinary observer is likely to vary 10 to 25 percent from the true figure. Furthermore, under the conditions generally prevailing in hearings and conferences, both time and patience for estimates of this kind are lacking. Chart 42 presents the same data as Chart 41, but with the amount corresponding to each segment clearly lettered on the bars. The seg- ment labels are placed above the first bar. One disadvantage of scaled charts is the difficulty in labeling the segments so they can be easily identified. Unless the labels are inserted below the scale, which inter- feres with the use of the scale for measuring the size of segments and bars, they generally have to be lettered at irregular intervals in the blank space at the right of the bars. ROBBERY South Atlantic East South Central Pacific New England 276 CHART 42. CRIME RATES IN URBAN COMMUNITIES (PER 100,000 POPU- LATION ) , BY GEOGRAPHIC DIVISIONS I 1943 ( DATA LETTERED ON BARS ) . There is nothing exaggerated or unusual about the foregoing example. The writer has witnessed many like it in hearings and conferences with congressional committees. The presentation of scaled charts, without 58 GRAPHIC PRESENTATION SIMPLIFIED all the data readily available in worksheets or tables, nearly always resulted in requests for exact information that could not be immedi- ately supplied. In business conferences the chart may bear on matters of policy to be considered later by agencies or firms represented in the meeting. Yet if scaled charts are used to present the data, all the individual repre- sentative can carry away with him is his general impression of the graphic picture, with such approximations as he may have been able to make from the scale. In lettering figures on bar charts two rules should be observed. If the lettering is within the bar, it should be small enough so that a strip of the shading or color shows above and below it. If at the end, the letter- ing should be less in height than the width of the bar and slightly sepa- rated from it. This will obviate the possibility of the observer comparing the combined length of bars and lettering, rather than the bars alone. 52 CHART 43. LETTERING WITHIN AND AT THE END OF BARS. An example in which the first of these rules was not followed is shown in Chart 44. The lettering is so large that it cuts each bar in half. Also, it is centered on the bars, so that the figure on the first bar, 222, falls directly below 120 on the scale. Bars without subdivisions should be lettered near the end. In segmented bars the lettering may be centered on or placed at the end of the segments. No scale was needed in Chart 44. The use of both lettered bars and a scale in the same chart is confusing. The ruling under each stub item is unnecessary. Except in charts with very wide stubs, connecting lines from stub titles to bars are not required. ORDER OF COMPONENTS AND RULING Bar charts are sometimes arranged in the alphabetical sequence of geographical or other units, as, for example, the States or counties of a BAR CHARTS 59 State, but in this order are usually ineffective and hard to interpret. In nearly all cases a descending or ascending order of values will afford a clearer presentation and save the reader the effort of deciphering the relationship between components. Ruling of bar charts other than that required for outlining the bars may be entirely omitted. Or it may be held down to a single rule con- necting the left end of the bars. The question of more or less ruling is a CHART 44. POST, CAMP, AND STATION STOCKS OF NON-PERISHABLE SUB- SISTENCE ITEMS. FROM STATISTICAL REPORTS TO THE QUARTERMASTER GENERAL. 60 GRAPHIC PRESENTATION SIMPLIFIED matter of taste and judgment, depending chiefly on whether it aids in understanding and interpreting the statistics presented in the chart. The same criterion applies to the use of borders, a frame extending around the four sides of the chart, including the title and footnotes or sources below the grid. In crowded charts the margin between the border lines and the over-all chart area reduces the space available for the drafting. LETTERING STUB ON BARS In Chart 45 the names of the components, ordinarily placed as stubs FEDERAL EXPENDITURES PER CAPITA 1946-47 FISCAL YEAR INT. FINANCE! 45 GENL.GOVT. II 36 Cleveland Trust Company Business Bulletin CHART 45. BAR CHARTS 61 at the left of the chart, are lettered on and at the end of the bars. Ex- treme condensation is sometimes necessary in charts for publication, where there is insufficient space for the conventional arrangement. In this chart lettering the component titles in stub form would have short- ened the space for the bars by about one third. JOINED-BAR CHARTS Bar charts are easier to read and are of better appearance if space is left between the bars, but if the chart includes a large number of items, spacing may have to be omitted. Generally the values can be lettered within the bars. If the bars are too narrow to permit this, the choice is between lettering at the end or in a column at the left of the base line. Chart 46, copied from a joined-bar chart of the forty-eight States, compares the two methods. In the upper chart the figures are lettered at the right of the bars, and in the lower, between the stub items and the base line. The position of the lettering is a matter of choice, although the first method is more generally used. NEW YORK PENNSYLVANIA ILLINOIS CALIFORNIA OHIO 1 9.9 | 13.5 7.9 17.0 I 6.9 NEW YORK 13.5 PENNSYLVANIA 9.9 ILLINOIS 7.9 CALIFORNIA 7.0 OHIO 6.9 12 CHART 46. POPULATION OF FIVE LARGEST STATES: 1940 (IN MILLIONS). q u o u i ^ 10' H 1 1 ~i i*> s * Q 1^ ': O 10 -< esj. > 'I T g ^ : 1 5 V 1 / c T- % 71 .*; ^ X 1 ^ O u. x \r>' Ul o Z < ^ '^ ^ Y////////////////////////////A V x v Y////////////////////////////A ^ ^ V/////////////////////////////J "." *r v////////////////////////////// r: - ;r ,. v Y/////////////////////////////A B ] * X '^ x ^ .'. ^ \ , x , i s ' x s. v v x * , s^ * x. x ^ s a \ *.* ^ ^ X V, , S ' s; ^ / .;.' S "O> ., \ V*. ^ , x x 'v \ . ' \ \ x , ^ 'x -' x v x X V \ x \ ; .\ ^^ s ^ ! , \ * x /. P * B v \ \* >v "' V * x 1 *, \ ,' t * r '' N ' \ V ^ * ,* <N V N - . *.* ^ V ^^ " , x \ < ^ ^ ,.' \ x x x s \ \ 5 'x < | >: ; - Z o O. ^ LU O too ZJ C C s l J ^ K K H ft *. V- \ > u 3 r- i r*> *~ 4 * s > -j u X i t ofc aE ^ Q. </ t: ) > O V) r> C j m Q U V ) .- c ) o 13 a ) ^ X > i. C3 r L C a a j ^ '' -c 1 a ^ Q " 1 4 j ^J . ) r t/ 3 (/ 5 ^ c ) c O c c T) fl c e [) 7) 9 ^ J - a - 1 ^ c J a +- u j > } r . t X L *k v <^ V ) .- ( > a > Q J 3 k_ v 7 O c r- C- > ) c L 3 T Ll 2 ) 3 4- > ! l 3" 2 (S 'a u ) > * a J c . &2 BAR CHARTS 63 GROUPED-BAR CHARTS This type, illustrated in Chart 47, is employed frequently for pictur- ing changes in two or more categories from one time period to another or for comparisons with an estimate, average, or forecast. In Chart 47 the diagonal bar represents the base of the index, 100, the dotted bar the September stocks, and the cross-hatched bar the forecast to March of the following year. While effective for comparing different aspects of a single component, comparisons between the components are difficult to interpret. In this example there are too many bars in each group and the groups are too close together. The use of grouped-bar charts should be limited, as a rule, to groups of two bars, with shading or color for each bar in marked contrast. The separation between groups should be around three quarters of the com- bined width of the bars. Groups of three bars or over present the eye with too many different comparisons at one time. KEYS If the bars include a considerable number of small segments, it may be necessary to use a key. This is usually placed at the right of the bars in the body of the chart, if space is available, or it may be lettered above the grid. Both methods are shown in Chart 48. TITLE WHEAT liiiliiiiiiiiii CORN R888&*! OATS Wtfftfa BARLEY PPIH ALL OTHERS BARS CHART 48. Two METHODS FOR PLACEMENT OF KEYS. 64 GRAPHIC PRESENTATION SIMPLIFIED The use of keys should be avoided as much as possible. Descriptive labels nearly always can be lettered over the first bar. Long labels may be lettered in two or three lines. PAIRED-BAR CHARTS This type is frequently used for comparisons of derived and basic MILES OF LINE NET INCOME PER MILE OF LINE ::i|:;:!:;i;iii|:;i!i!!n;i| JAPAN 10,469 i33,500;i 4,669 GERMANY 1935 SWEDEN 1935 $315 $177 liilllllilllllllll AUSTRALIA (STATE) 1935 (FEDERAL) 1935 8..4S I DEFICIT PER MILE OF LINE $208 $1,072 NORWAY 2,265 pi (STATE) 1936 '.".IE $296 National Industrial Conference Board CHART 49. NET INCOME OR DEFICIT OF GOVERNMENTALLY OWNED OR OPERATED RAILWAYS IN VARIOUS FOREIGN COUNTRIES: 1935 OR 1936. BAR CHARTS 65 data. The purpose of the comparison in Chart 49 is to show the degree of success attained by various countries in the administration of govern- mentally owned or operated railways. The bars of the positive category, net income per mile of line, are arranged in descending order, from the largest to the least. The order of the negative category, deficits per mile of line, is reversed, the series beginning with Australia, which showed the smallest deficit, and ending with France, the largest. The bars on the left side of the chart indicate the size of the various railway systems. COMPLETION OF TERMINATION INVENTORY WORKLOAD AUGUST - NOVEMBER 1945 DEPOT WORKLOAD 1 AUG- 30 NOV ($000) PERCENT COMPLETED Total Philadelphia Jersey city Jeffersonville Chicago Boston Others 206,344 60,786 11,440 59,143 61,429 7,602 5,994 ^HO^ JL*+-Auguat- October A l^^i^^^^i^^CNXVW^^J ^^57 4^ Mm ^. Jk ^ ^^p^ A ?~;^ s K;^ A ^^^wr?^ A CHART 50. CONTRACTOR-OWNED TERMINATION INVENTORY. FROM STA- TISTICAL REPORTS TO THE QUARTERMASTER GENERAL. BAR-AND-SYMBOL CHARTS A combination of bar and symbol is sometimes used in charts of grouped data. In Chart 50 the bar represents the percent completed through August to November. The pyramidal symbol indicates the cor- 66 GRAPHIC PRESENTATION SIMPLIFIED responding percent through August to October. Various types of sym- bols are employed. One frequently seen consists of a short vertical line intersecting the bar or placed at the right in line with it. The symbol device is usually less effective than grouped bars. Only a rough approximation of the amount indicated by the symbol is pos- sible, while a bar employed for the same purpose permits clearer plot- ting and lettering of the exact amount. Another difficulty is met with where the amounts represented by the symbols are greater than those of the bars. In such cases the symbol may be separated so far from the bar PERCENT OF TOTAL WORKING EXTRACTION OF MINERALS AND FORESTRY MANUFACTURING AND MECHANICAL INDUSTRIES NOT SPECIFIED INDUSTRIES X AND SERVICES PERCENT COVERED PERCENT NOT COVERED 4.2 29.4 15.4 2. TRANSPORTATION AND Q , COMMUNICATION **' ' C ^DOMESTIC AND PERSONAL SERVICE PROFESSIONAL SERVICE AGRICULTURE, FISHING AND PUBLIC SERVICE 23.8 National Industrial Conference Board CHART 51. PROPORTION OF WORKING POPULATION COVERED BY THE OLD AGE PROVISIONS OF THE SOCIAL SECURITY ACT, USING THE DISTRIBUTION OF OCCUPATIONS OF THE 1930 CENSUS. BAR CHARTS 67 that the relation between the two is not clearly apparent. If there are a number of such items in the chart, the effect is extremely confusing. AREA-BAR CHARTS This form of 100 percent bar chart shows both the percentage dis- tribution of the categories and the relative size of the components. In Chart 51 the figures in the bars represent the percent in each group which are covered and not covered by the provisions of the Social Security Act. The figures at the left indicate the proportion of the total working force in each group. Unless the size of the component items is shown graphically in per- centage-distribution charts, it is advisable to include in a column fol- lowing the stub the figures from which the percents are derived. Comparisons of percentage distributions unaccompanied by the basic data do not provide sufficient information for a correct interpretation of the relative figures. OPTICAL DISTORTION IN BARS Care must be exercised in the choice of shadings to avoid combina- tions which produce optical distortions. Chart 52 shows the "bending" effect which results when two diagonal patterns are used and the appar- ent increase in the width of one segment when solid black and a hori- zontal line shading are combined. If bar charts are to be printed, the use of solid black in segmented bars should be avoided. Shading comes out lighter in printing than in DIAGONAL SHADING MAY "BEND" THE COLUMNS SHADING MAY AFFECT APPARENT WIDTH CHART 52. OPTICAL DISTORTIONS. 68 GRAPHIC PRESENTATION SIMPLIFIED the drawing. When solid black and shading are used in the same bar, the black segment stands out more prominently than the shading, there- by overemphasizing the category it represents. INCLUSION OR OMISSION OF 100 PERCENT BASE It is desirable in percentage charts to show a measure which repre- r EM A B C D PERCENT ^ IC Perc )O ent 140 125 94 | 76 ITEM A B C D PERCENT IOO Percent I ITEM PERCENT A B C D II 9 i 4 CHART 53. INCLUSION OR OMISSION OF 100 PERCENT BASE. BAR CHARTS 69 sents the 100 percent base. If the figures approach or exceed 100, as in the upper example in Chart 53, the base may be indicated by a vertical dash line. If all the percentage figures are small, however, the 100 per- cent horizontal scale is likely to leave too little space for an effective comparison, and in such cases it should be omitted. For example, the inclusion of a base line in the second chart dwarfs the length of the bars. In the lower chart the base has been omitted, thus permitting the full width of the chart to be utilized for a clearer comparison of the per- centage figures. DEVIATION-BAR CHARTS This design is frequently used for comparisons of positive and negative quantities, increases and declines, losses and gains, or de- viations from a standard or norm. The bars extend to the left and right of a vertical base line. The "positive" bars are generally arranged in descending order of sequence and the "negative" bars in ascending order. Chart 54 illustrates a problem frequently encountered in charts of this type. The length of the negative "Subsistence" bar imposes a wide separation between the bars and stub titles of the other items of the series. This can be overcome by lettering the stub titles opposite the GROUP OF ITEMS PERCENTAGE CHANGE, JANUARY TO FEBRUARY 1944 DECREASE INCREASE All QM Items Equipage General Supplies Textiles Clothing Subsistence ill HO.. ange No ch ^3W>^^^-^^^^^^^^^ KV, '* ,Vi', ViVxViV^VxV*', '.V.V, ,*' V.VAVVAVx'.'.'. ' CHART 54. PRICE CHANGES. FROM STATISTICAL REPORTS TO THE QUARTER- MASTER GENERAL. 70 GRAPHIC PRESENTATION SIMPLIFIED bars, within the body of the chart, as shown in Chart 55. By this method the stub titles are placed closer to the bars and more space is available for the graphic comparison. ARMY FUNDS UNCOMMITTED MILLIONS FEB 28, 1942, AND JAN 31. 1942 DECREASE INCREASE Air Chemical Warfare Signal 168 Medical 1 19 1,889 164 ^| Quartermaster 561 BfHHJI Engineers Ordnance CHART 55. FROM Manual of Statistics, WAR DEPARTMENT, SOS. BASE FIGURES IN CHARTS OF RELATIVE NUMBERS In bar charts of averages, percentages, or other relative numbers, the item representing the combined figure for the whole series may be set off, as' in Chart 56, by larger lettering. Various other methods are em- ployed to distinguish it from the accompanying items: wider space above and below its bar and stub, a different shading or color, a bar BAR CHARTS 71 CONSUMERS' PRICES % INCREASE, MAY 1947 OVER 1935-39 AVERAGE FOOD CLOTHING HOUSE FURNISHINGS ALL ITEMS MISCELLANEOUS FUEL, ICE, ELECTRICITY RENT 88% 84% 82% 56 /o 39/o !8/o I Cleveland Trust Company Business Bulletin CHART 56. wider than the others; or by placing it at the beginning of the series in- stead of in order of size. A common practice, if the last method is used, is to extend a vertical dash line from the end of the "All items" or "Total" bar through the bars below it. ADJUSTMENT OF STUB TO SPACE One of the faults most frequently observed in bar charts results from the common practice of fitting the stub space to the longest component 72 GRAPHIC PRESENTATION SIMPLIFIED title. As the bars constitute the graphic part of the chart, as much as possible of the horizontal space should be allotted to them. Long titles should be shortened by editing and abbreviation and, if necessary, by lettering in two or more lines. Chart 57 shows a comparison of two charts with identical stubs, the first with all item titles lettered in single lines, and the second with the longer titles lettered in two lines. The effect of shortening the stub of the lower chart in this way increases the space for the bars nearly one half. The bars are brought closer to the item titles, with marked improvement in the general appearance of the chart. GROUP EMPLOYMENT Manufacturing Trade Government: Federal, State and Local Finance, Service and Miscellaneous Transportation Government : Federal , State and Local Finance, Service and Miscellaneous CHART 57. ESTIMATED NON-AGRICULTURAL EMPLOYMENT, FIVE LARGEST INDUSTRIAL GROUPS: LAST QUARTER, 1945 ( IN THOUSANDS). BAR CHARTS 73 STEP-BAR CHARTS Chart 58 shows a design sometimes used instead of the conventional stub and bar arrangement for picturing the subdivisions of a total if their number is too large for an effective presentation in a single bar. The relation of the subdivisions to the total is somewhat clearer than if the bars were placed immediately following the stub titles. EUROPE NORTH AMERICA ASIA SOUTH AMERICA AFRICA OCEANIA CHART 58. EXPORTS (INCLUDING REEXPORTS), UNITED STATES, BY CON- TINENTS: 1940 (IN MILLIONS OF DOLLARS). UJI- o:c/) ( (/) . 000 74 BAR CHARTS 75 SLIDING-BAR CHARTS A variation of the deviation-bar type, sometimes designated "sliding- bar," is shown in Chart 59. It presents a large volume of data condensed without sacrifice of simplicity and clarity within a small amount of space. Economy of space is secured partly through the elimination of all scales and ruling not absolutely essential and partly through lettering the stubs, in this case years, over the base line of the bars instead of at the side of the chart. The original from which this chart was copied was in two colors, blue in two shades for investments and red in three shades for loans. Color offers many advantages over black-on-white shading for charts of multi- segmented bars. COLUMN CHARTS 'OLUMN charts are bar charts arranged vertically. Their most frequent use is for picturing com- parisons of similar components at different times, while bar charts are generally employed to compare different components at the same time. The column design is particularly effective for the presentation of series which comprise a small number of time periods with few subdivisions of value. It is not well suited for comparisons of several time series nor for those which cover an extended period of time and have many plottings. COLUMN AND SEGMENT LABELS Column charts are considerably more difficult to design than bar charts, chiefly because of the problems they present in labeling seg- mented columns. Segments in bar charts can be clearly labeled over the first bar, while in column charts the labels are lettered across the col- umns or at the left or right side of the chart. Lettering of segments on 76 COLUMN CHARTS 77 the left side is usually not practicable if the first column is much shorter than the others nor on the right side if the chart is to be brought up to date at recurring intervals. In the latter case the labels, lettered on separate strips of paper, may be pasted with rubber cement at the right of the last column and shifted for future entries. Chart 60 illustrates the method commonly employed for segment labeling at the left of the chart. The dash lines connecting the segments should be included in column charts, unless the spaces between the columns are very narrow or there is marked irregularity in the size of the segments. Total during month Disposal*, re- distributions and transfers On hand at_ end of onth \\...r v \ 22,733 24,010 m SEP OCT CHART 60. DISPOSITION OF SURPLUS PROPERTY: JUNE TO DECEMBER, 1944 (THOUSANDS OF DOLLARS). FROM Statistical Yearbook, QUARTER- MASTER CORPS. COMPARISON OF COLUMNS WITH CURVES Since the introduction of adhesive shading and color, the column type has supplanted curves to a considerable extent in charts of time series. This has come about chiefly because making a column chart with the new material represents little if any more work than would be re- quired for drafting the same data as curves, while improved appear- ance and more striking contrast can be secured through use of color or 78 GRAPHIC PRESENTATION SIMPLIFIED MILLIONS OF DOLLARS Other Sales Automobile Sales Loans 6000 5000 4000 3000 2000 000 1939 1940 1941 1942 1943 1944 1945 CHART 61. INSTALMENT CREDIT: 1939 TO 1945 (COLUMN DESIGN). shading. To the non-statistical observer a series in columns appears simpler and easier to understand than the same data plotted in a curve design. Charts 61 and 62 illustrate some of the advantages and disadvantages COLUMN CHARTS 79 MILLIONS OF DOLLARS 2400 2000 MILLIONS OF DOLLARS ~*2400 2000 1600 1200 800 400 1600 1200 800 400 1939 1940 1941 1942 1943 1944 1945 CHART 62. INSTALMENT CREDIT: 1939 TO 1945 (CURVE DESIGN). of each type. The columns compare more effectively than the curves the amounts of credit extended in each category but, because two of the segments have no common base, do not indicate as clearly the trend or direction of change. For the latter purpose, in most cases the curve chart, in which all the curves are plotted from the same base, is gen- erally preferred. 80 GRAPHIC PRESENTATION SIMPLIFIED TO France MAY JUM JUL AUG SOTOCT MOV DEC JAT1 FEB KAftAPR MW JUfl JUL AU6 5EPTOCT HOX DEC JAfl FEB MIR APR HAY JUM 1917 1918 1919 CHART 63. MEN SAILING EACH MONTH TO FRANCE AND HOME: 1917 TO 1919. FROM The War with Germany, BY LEONARD P. AYRES. HOLLOW COLUMNS Hollow columns representing simple comparisons of size can be used effectively in charts intended for printed reproduction, as illustrated in Chart 63. The ruling and lettering of the black portion of the chart were done with white ink. The columns are so narrow and the figures so large it was necessary to disregard the rule against vertical lettering. Single letters might well have been substituted for the three-letter abbrevia- tions in the time scale, which is too crowded for easy reading. COMBINATION OF SPACED AND JOINED COLUMNS The spaced columns in Chart 64 represent yearly averages from 1939 to 1944. The joined columns show the data by months in 1945. The COLUMN CHARTS 81 300 300 250 200 150 100 1939 1940 1941 1942 1943 1944 J F M A M J J A 1945 S CHART 64. INDUSTRIAL PRODUCTION, MANUFACTURES: 1939 TO 1945 (1935-39 AVERAGE = 100). average is indicated by the dash line intersecting the monthly columns. Amount-scale ruling was necessary, as the monthly columns are too narrow for lettering the values. For the same reason the months in the 82 GRAPHIC PRESENTATION SIMPLIFIED time scale are represented with single letters instead of the three-letter abbreviations usually employed for this purpose. The choice between spaced and joined columns depends on the length of the time series. In long time series spacing necessarily is omitted. In short series fairly wide spacing between columns, at least the width of the columns, gives a better appearance than narrow spaces and wide columns. COMBINATION OF CHART AND TABLE If the columns are too narrow for lettering, as in Chart 65, a table containing the data may be lettered within the grid field. This method is limited to small charts for publication or for desk use. It is not usually INDUSTRIAL PRODUCTION 1937 1938 1939 1940 1941 1942 1943 1944 1945 Cleveland Trust Company Business Bulletin CHART 65. COLUMN CHARTS 83 practicable in display charts. If the lettering is large enough to be legible at some distance, the table will take up too much space. GROUPED-COLUMN CHARTS This type is fairly effective if the number of columns in each group does not exceed two. Groups of three or more complicate the compari- sons between the categories in the various groups to the extent that interpretation of the chart becomes difficult. The columns should be clearly differentiated by contrasting colors or shading. In Chart 66 keys are employed to identify the categories represented by the columns. The use of keys should be avoided, but the alternative in grouped-column charts labeling the columns in the space above the groups is equally objectionable. Key labels may be omitted, as in this 600 500 400 300 200 100 HEAVY AND LIGHT BOMBERS ACCEPTED - 1942 JAN FEB MAR APR MAY JUN CHART 66. FROM Manual of Statistics, WAR DEPARTMENT, SOS. 84 GRAPHIC PRESENTATION SIMPLIFIED example, by placing the key directly under the corresponding designa- tion in the title. Another method, if color is used, is to letter the name of each component or category in the title in the same color employed to designate it in the chart. In Chart 67 one category is represented by columns and the other by circles connected with lines. This method permits clear lettering of each category. It is most effective for comparisons in which the values do not vary widely in size. Par. 1.8 2.3! 2.5 3.6 2.9 :2.5: 1938 1939 1940 1941 1942 1943 1944 1945 CHART 67. PAR AND MARKET VALUES OF BONDS SOLD ON NEW YORK STOCK EXCHANGE: 1938 TO 1945 (BILLIONS OF DOLLARS). COMBINATION OF COLUMNS AND CURVES An example of joined columns combined with a curve and surface overlay is -shown in Chart 68. The solid curve represents expendi- tures, and the ball-and-line curve receipts. The deficits from 1917 to 1920, when expenditures exceeded receipts, are indicated by dotted shading. The space corresponding to the surplus from 1920 to 1930, COLUMN CHARTS 85 RECEIPTS, EXPENDITURES, AND NATIONAL DEBT FEDERAL GOVERNMENT, UNITED STATES, 1 91 3-1 936 FISCAL YEARS ENDING JUNE 30 EXPENDITURES RECEIPT^ I9I3'I4 15 16 17 18 *I9'20'2I '22'23'Z4. '25*26 '27 *28*Z9 30 '31 National Industrial Conference Board CHART 68. 86 GRAPHIC PRESENTATION SIMPLIFIED when receipts exceeded expenditures, is filled in with a heavy black shading. Yearly deficits began again in 1931 and continued through 1936. The amount scale is repeated at the right of the chart. This is usually desirable in charts covering long periods of time. The gross debt totals are lettered at the points of chief interest, the peak after World War I, the lowest point reached in the following eleven years, and the end year of the series. CHARTS SHOWING BOTH BASIC DATA AND PERCENTAGE DISTRIBUTION In charts where the purpose of the presentation requires that both the basic data and the percentage distribution appear, various methods are used to show both sets of figures. A small table of the percents or the amounts, whichever is least important, may be attached to or lettered on the chart. This procedure is seldom used, however, as it does not tie the series together closely enough for convenient reference and comparison. Another method commonly employed, illustrated in Chart 69, consists in lettering both series on the columns. The basic figures are lettered above or within the columns and the percents below in smaller lettering, followed by the percent sign. The figures may be further dif- ferentiated by enclosing the percents within parentheses. Or the per- cents may be lettered immediately above the base line or centered on the columns. 24O 24O (18%) 24O 240 18% 18% "~ L 18% X \> *V CHART 69. METHODS FOR LETTERING BASIC AND PERCENTAGE FIGURES ON N^^ COLUMN CHARTS. X COLUMN CHARTS 87 The design shown in Chart 70 is frequently employed where a graphic comparison of the basic data with the percentage distribution is desired. The lettering of the segment labels between the charts, in- stead of at the left of each of them, one set of labels thus serving for both charts, saves space and facilitates the comparison. AMOUNT (Millions) 4.239 Total PERCENT DISTRIBUTION 100.0 100.0 1932 CHART 70. 1945 1932 1945 INTEREST PAYMENTS ON DEBT OF FEDERAL, STATE, AND LOCAL GOVERNMENTS: 1932 AND 1945. GRAPHIC PRESENTATION SIMPLIFIED DEVIATION-COLUMN CHARTS This type, consisting of columns above and below a common base line, is used, like the deviation-bar chart, for comparisons of positive and negative values and variations from a standard, estimate, or fore- cast. Charts 71 and 72 show two arrangements of the time scale. In the first, space sufficient for lettering the years forms the base separating the columns. In the second, the years are lettered below the chart and connected with the columns by dotted lines. Exports 1915 1925 !935 1945 Imports 1,674! i 2,047; 4,227 CHART 71. TOTAL EXPORTS AND IMPORTS OF MERCHANDISE: 1915, 1925, 1935, AND 1945 (MILLIONS OF DOLLARS). COLUMN CHARTS 89 If the chart is for printed reproduction, the figures of the time scale may be pasted on the base line between each pair of columns. The let- tering should be small enough to leave a strip of shading or color be- tween the figures and the column rulings. If the difference in the size of columns is extreme, as in Chart 72, lettering on the base line is imprac- ticable. DOMESTIC CORPORATE SECURITY ISSUES UNITED STATES, 1919 - 1937 COMPARISON OF NEW CAPITAL ISSUES WITH REFUNDING ISSUES 1923:1924 1925 ! 1920 1927 1928 1929 1930 1931 ! 1932 I 1933 i 1934 I 1935 1 I93 i 1937 National Industrial Conference Board CHART 72. CIRCLE CHARTS 'OMPARISONS of size are much easier to interpret correctly from bars or columns than from circles, squares, cubes, or spheres. The use of various geometric forms for graphic purposes is compared in Chart 73. The second column in the first chart is exactly twice the height of the first column, but if the same amounts are drafted in the form of circles or squares, the difference between them appears to be considerably less. This effect is still more noticeable in the comparison of the same set of figures as cubes or spheres. COMMON ERRORS IN DRAFTING CIRCLES There is probably a higher percentage of errors in the drafting of circle charts than is found in any of the other graphic types, chiefly because of the complicated procedure for calculating the diameters of circles. The rule is: Divide the number represented by the circle by .7854 and extract the square root of the quotient. Unless the worksheet 90 CIRCLE CHARTS 91 USE OF DIFFERENT GEOMETRIC FORMS IN COMPARING SIZES 1 ^1 | 1 PLANES PLANES PLANES PLANES PLANES PLANES IN NOV. IN MAY IN NOV IN MAY IN. NOV IN MAY 5,000 10,000 5,000 10,000 spoo 10,000 LINES, BARS OR COLUMNS AREAS VOLUMES Easy to compare Difficult to compare Yery difficult to compare oO oO Q Q PLANES PLANES PLANES PLANES PLANES PLANES IN NOV. IN MAY IN NOV. IN MAY IN NOV IN MAY 5,000 IOPOO 5,000 10,000 5,000 10,000 DIAMETERS OF CIRCLES AREAS OF CIRCLES VOLUMES OF SPHERES PROPORTIONAL PROPORTIONAL PROPORTIONAL TO NUMBERS TO NUMBERS TO NUMBERS .All circle types are difficult to compare and should seldom be used. CHART 73. FROM Manual of Statistics, WAR DEPARTMENT, SOS. shows the correct diameters or radii, the draftsman, who has probably forgotten the rule if he ever knew it, is likely to fall back on the easier but erroneous method of making the diameters proportional to the size of the numbers. Chart 73 shows an example of the distortion in circle charts where the diameters instead of the areas of the circles represent the numbers com- pared. The first chart in the lower row, in which the diameters of the circles are proportional to the numbers, greatly exaggerates the differ- ence between the amounts compared. SHORT-CUT METHOD FOR CALCULATING THE SIZE OF CIRCLES The use of the following method, combined with the table of square roots shown on page 93, will save time and tedious computation in calculating the size of circles. 92 GRAPHIC PRESENTATION SIMPLIFIED RULES A. Divide the smaller number by the larger. Express the quotient in a decimal of not more than two digits. B. Extract the square root of this quotient. (Table III lists the square roots of decimals from .01 to .99 to three places. ) C. Multiply the square root by the predetermined diameter of the larger circle. The product will be the diameter of the smaller circle. Example: Larger number, 500; smaller number, 100. Diameter of larger circle, 6 inches. A. 100 divided by 500 equals .20. B. Square root of .20 equals .447. C. .447 multiplied by 6 inches, diameter of larger circle, equals 2.7 inches, the diameter of the smaller circle. Large numbers should be rounded to not more than three digits. This will shorten and simplify the calculation considerably, and the quotients will be the same, for drafting purposes, as if the full figures were used in the division. The extraction of the square root, which generally is the stumblingblock for the draftsman, is covered by the table. Table 'II illustrates the procedure for calculating the diameters of a number of circles representing figures that vary widely in size. The assumed diameter of the largest circle is 9 inches. TABLE II CALCULATION OF CIRCLE DIAMETERS Amounts B, C, D Di- Square Square Root Component Amounts Rounded vided by A Root Times 9 Inches A 126,765 127 B 88,441 88 .69 .831 7.5 inches C 37,552 38 .30 .549 4.9 D 25,224 25 .20 .447 4.0 If a slide rule is used to compute the component ratios and multi- plication of the square roots, the calculation of the circle diameters for a chart of five to ten circles should not take more than fifteen min- utes. The diameters of the smaller circles (square roots multiplied by the diameter of the largest circle) should be rounded to one decimal place. Drafting to hundredths of an inch is impracticable. CIRCLE CHARTS 93 TABLE III SQUARE ROOTS OF DECIMALS .01 TO .99 Deci- Sq. Deci- Sq. Deci- Sq. Deci- Sq. mal Root mal Root mal Root mal Root .01 .1 .10 .316 .40 .632 .70 .837 .015 .125 .11 .332 .41 .640 .71 .843 .12 .346 .42 .648 .72 .849 .02 .141 .13 .360 .43 .656 .73 .854 .025 .158 .14 .374 .44 .664 .74 .860 .03 .173 .15 .387 .45 .671 .75 .866 .035 .187 .16 .4 .46 .678 .76 .872 .17 .412 .47 .685 .77 .877 .04 .2 .18 .424 .48 .692 .78 .883 .045 .213 .19 .436 .49 .7 .79 .889 .05 .224 .20 .447 .50 .707 .80 .894 .055 .235 .21 .458 .51 .714 .81 .9 .22 .469 .52 .721 .82 .906 .06 .245 .23 .480 .53 .728 .83 .911 .065 .255 .24 .490 .54 .735 .84 .917 .07 .265 .25 .5 .55 .742 .85 .922 .075 .274 .26 .510 .56 .749 .86 .927 .27 .520 .57 .756 .87 .933 .08 .283 .28 .530 .58 .762 .88 .938 .085 .292 .29 .540 .59 .768 .89 .943 .09 .3 .30 .549 .60 .775 .90 .949 .095 .308 .31 .557 .61 .781 .91 .954 .32 .566 .62 .787 .92 .959 .33 .575 .63 .794 .93 .964 .34 .584 .64 .8 .94 .970 .35 .592 .65 .806 .95 .975 .36 .6 .66 .812 .96 .980 .37 .608 .67 .819 .97 .985 .38 .616 .68 .825 .98 .990 .39 .624 .69 .831 .99 .995 94 GRAPHIC PRESENTATION SIMPLIFIED NEW INDUSTRIES AND EMPLOYMENT UNITED STATESJ879 AND 1929 AVERAGE NUMBER OF WAGE-EARNERS, MANUFACTURING INDUSTRIES, PER MILLION OF TOTAL POPULATION 1879 49,437 WAGE-EARNERS 1929 72,731 WAGE-EARNERS 18 NEW INDUSTRIES 9,243 13% ALL OTHER INDUSTRIE 3,4881 87% INCREASE, 1929 OVER 1879 23.294 WAGE -EARNERS National Industrial Conference Board CHART 74. NEW INDUSTRIES AND EMPLOYMENT (CIRCLE DESIGN). CIRCLE CHARTS 95 CIRCLES COMPARED WITH BARS A comparison of circles and bars for picturing differences in size, with sectors and segments for subdivisions within components, is shown in Charts 74 and 75. The upper circle in Chart 74 represents the num- ber of manufacturing wage-earners per million of population in 1879, the middle circle the corresponding number in 1929, and the lower cir- cle the increase that took place over the fifty years covered by the com- parison. The sectors show the proportions of the increase contributed by old and new industries. Chart 75 presents the same data in a bar design. It shows more clearly than the circle chart the comparison between the totals for the two years and the extent of the increase contributed by new and old in- dustries. Comparisons of size in the form of circles have the effect of lessening the apparent difference between the quantities compared. The amount represented by the 1879 circle, for example, appears to be not far below that shown by the 1929 circle, although the latter ex- ceeds it by over 47 percent. 1879 1929 Increase 1929 over 1879 49,437 New In- dustries All Other Industries :9,243; 13%: 63,488 87%: 72,731 :: 1 40 5 1 :::-. 23,294 CHART 75. NEW INDUSTRIES AND EMPLOYMENT (BAR DESIGN SECTOR CHARTS iMONG statisticians and drafts- men the common designation for a sector chart is "pie" chart. It is less effective than bar and column designs for accurate reading and inter- pretation, particularly if the series contains a considerable number of components or if the difference between components is slight. The com- ponents "Small Arms" and "Artillery" in Chart 76, which compares sector and bar designs, are an example. In the sector chart they appear to be almost the same size, while in the bar chart below the difference between them stands Out clearly. The eye can compare linear measure- ments more accurately than it can areas of sectors or arcs of a circle. ORDER OF SECTORS The standard practice in drafting sector charts is to begin with the largest sector at the central point of the upper half of the circle. The arrangement of sectors is from right to left in order of size. If the chart contains an "All Other" or "Miscellaneous" sector representing a num- 96 SECTOR CHARTS 97 DISTRIBUTION OF VALUE OF EQUIPMENT - BY MAJOR GROUP FIRE CONTROL EQUIPMENT ARTILLERY 80% SMALL ARMS AUTOMOTIVE MATERIEL 20% DISTRIBUTION OF VALUE OF EQUIPMENT - BY MAJOR GROUP PERCENT OFTOTAL 20 40 60 AUTOMOTIVE MATERIEL SMALL ARMS ARTILLERY FIRE CONTROL EQUIPMENT CHART 76. COMPARISON OF SECTOR AND BAR CHARTS. ADAPTED FROM Standards of Presentation, ARMY SERVICE FORCES. 98 GRAPHIC PRESENTATION SIMPLIFIED Semi- Manufactures 23% Manufactured Foodstuffs Finished Manufacturers 16% Semi- Manufactures 23% CHART 77. IMPORTS, UNITED STATES, BY ECONOMIC CLASSES: 1942. SECTOR CHARTS 99 her of small components, this is placed last in the series of sectors, irre- spective of its rank in order of size. LETTERING OF SECTOR CHARTS Sector charts should not be lettered radially, following the angle of the individual sectors. The lettering of component titles should be hori- zontal, within the sector if not too crowded, outside the circle if the sector is too small to carry the lettering horizontally. The figures should be lettered, if possible, within the sectors. The two methods are illus- trated in Chart 77, which represents a percentage distribution, by eco- nomic classes, of United States imports in 1942. As the title of the last sector is too long for horizontal lettering within the circle, it is placed outside, with a connecting arrow to the sector. GROUPING OF SECTORS Grouping of sectors may be indicated in various ways. A curved line drawn outside the circle, extending between the limits of the group and lettered with the group designation, is commonly employed for this purpose. Another method, illustrated in Chart 78, consists of a nar- row band of shading placed around the grouped sectors. NUMBER TOTAL PROCUREMENT DEPOT AWARDS, 93.1 (Thousands) VALUE TOTAL PROCUREMENT DEPOT AWARDS, $1,437 (Millions) CHART 78. CONTRACT AWARDS TO SMALL FIRMS: 1944. FROM Statistical Yearbook, QUARTERMASTER CORPS. 100 GRAPHIC PRESENTATION SIMPLIFIED MINIATURE SECTOR CHARTS The sector type in miniature sizes may be used effectively for com- paring in a single chart a considerable number of components sub- divided into percentages or broken down on some other basis. The accompanying example, Chart 79, represents the troop distribution by source of sixteen National Guard divisions in World War I. The black portion of each circle shows the part of each division drawn from the National Guard, the shaded portion represents troops drawn from the National Army and other sources, and the unfilled gap the proportion each division was short of its authorized strength when it sailed from this country. The names of the States from which the National Guard 32- 33* 34 th 36* 38* 40" CHART 79. COMPOSITION OF NATIONAL GUARD DIVISIONS, WORLD WAR I. FROM The War with Germany, BY LEONARD P. AYRES. SECTOR CHARTS 101 contingents were drawn are lettered in white on the black sectors. The figures outside the circle to the left are the division numbers. SEPARATION OF SECTORS FOR EMPHASIS The importance of an individual sector may be emphasized by the method illustrated in Chart 80. This variation in design is little used. It is frequently criticized as tending to concentrate the attention solely on a single feature of the chart. CAUSES OF DELAYS IN MAY DELIVERIES SIGNAL CORPS - 1942 OTHER SHORTAGES IN MATERIAL CONFLICTING CONTRACTS SHORTAGES IN EQUIPMENT PERSONNEL DIFFICULTIES CHART 80. ADAPTED FROM Standards of Presentation, ARMY SERVICE FORCES. OMISSION OF SHADING Sector charts do not require strong contrasts. Charts of this type with all shading omitted, although not as striking in appearance, are often quite as effective in conveying a correct impression of the relative values as would be secured with shading or color. If the titles are long, the 102 GRAPHIC PRESENTATION SIMPLIFIED lettering will occupy so much space within the sectors that most of the advantage of contrasting shading is lost. In Chart 81, for example, the titles of the fourth and fifth sectors are so long that nothing would be gained by surrounding them with narrow strips of shading. Overloading is the commonest fault in the planning and drafting of sector charts. If the number of sectors exceeds five or six, the lettering is likely to be crowded and confusing, with too many patterns of shad- ing or varieties of color. Simplicity, the first essential in all charts, is of special importance in designs of this type. PRO- FESSIONAL: PERSONS 1.8 UNSKILLED WORKERS SKILLED WORKMEN AND FOREMEN 6.0 PROPRIETORS, MANAGERS AND OFFICIALS 8.7 SEMI-SKILLED WORKERS 7.3 CHART 81. DISTRIBUTION OF MALE LABOR FORCE 14 YEARS OLD AND OVER, UNITED STATES: 1940 (IN MILLIONS). SECTOR TOTALS Totals of a number of components should not be represented by interior arcs drawn across the sectors. Chart 82, in which the lower arc represents the sum of the expenditures by the War and Navy Depart- ments, although the total corresponds in actual size to the larger arc of the circumference, is an example. Subdivisions of a total may be shown SECTOR CHARTS 103 by light dash lines, as in the second chart, or by different patterns of shading, but the total should be lettered outside the circle. TOTAL MILITARY SI, 368 CHART 82. MILITARY EXPENDITURES, UNITED STATES: 1939 (MILLIONS OF DOLLARS). IX STATISTICAL MAP CHARTS lAP charts are employed to show the geographical distribution of statistical data. If they are to be small-sized, map charts are generally made with outline maps on which the boundary and division lines of the geographical units are printed. Outline maps on paper, ranging from letter size to several feet square, can be obtained from firms specializing in map production. The outlines for display maps on illustration board, where no copy of the size re- quired is available, must be drafted. This is a difficult job, but a photo- stat of a small map blown up to the dimensions of the display outline will serve as a useful guide in the lay-out and drafting of the display- size map. About all a small map chart can accomplish graphically is to indicate the geographical distribution of the data, with a rough measure of the gradation in size of the numerical components. Attempts to show fine distinctions and small differences are nearly always ineffective. They only complicate and render more difficult a clear understanding of the general purpose for which the chart is planned. 104 STATISTICAL MAP CHARTS 105 USE OF COLORS Solid colors and colored shadings are generally used on maps not in- tended for printed reproduction, although the effect of gradual transi- tion from high to low volume or size of the categories is not as clear as with black shadings. Red is often used to designate the highest category, blue and green for the next two, followed by shadings of these colors, with yellow for the lowest category. Care should be taken to avoid harsh color contrasts. Light tints are more effective and have a more pleasing appearance than dark colors. MAPS WITH SURFACE DESIGNATIONS OF CATEGORIES The method most generally used for charting statistical data in maps is illustrated in Charts 83 and 84. Chart 84 is a section of a United States CHART 83. PERCENT OF DRAFTED MEN PASSING PHYSICAL EXAMINATION, BY STATES, WORLD WAR I. TAKEN FROM The War with Germany, BY LEONARD P. AYRES. 106 GRAPHIC PRESENTATION SIMPLIFIED 1,000 to 4,000 500 to 1,000 100 to 500 Vnder 1 00 CHART 84. NUMBER OF CONTRACTS AWARDED IN EACH STATE IN 1944. FROM Statistical Yearbook, QUARTERMASTER CORPS. STATISTICAL MAP CHARTS 107 map representing the distribution by States of quartermaster depot contract awards in 1944. The grouping of the data in six categories is indicated by the key at the lower right of the chart. This type of map chart is the clearest and easiest to read and costs the least in labor and time for drafting. As the adhesive colors and shadings come in large sheets, an application for a single category may cover half or, with small maps, all of the surface. The areas which are not in that particular category can be cut out in a few minutes. If figures for each geographical unit are shown, the color or shading is afterward cut out around them so they will stand out clearly. Or the figures, let- tered on strips of white paper, can be pasted in each geographical unit. The outline for Chart 84 was smoothed to save the time required for duplicating the exact configuration of the bays and inlets of the Atlantic Coast and the windings of State river boundaries. The use of white space to represent one of the categories is illustrated in Chart 83, page 105. It is fully as effective as the addition of a fourth shading would have been. DOT MAPS In Chart 85 the distribution of values is shown by small dots of equal size plotted by localities within the States. The drafting of a chart of this type is laborious and time-consuming. Each dot represents an indi- CHART 85. RURAL REHABILITATION CASES RECEIVING ADVANCES OF CAPITAL OR GOODS: 1935. FROM Rural Youth on Relief, WPA, DIVISION OF SOCIAL RESEARCH, 1937. 108 GRAPHIC PRESENTATION SIMPLIFIED vidual plotting. The number of plottings in this chart runs to over one thousand. The use of dots on map charts is open to the objection that in locali- ties of high concentration, where the dots overlap, no variation in the data can be shown. The area becomes a black cloud on which no addi- tional plottings will register. MAPS WITH CIRCLES Chart 86 is a section of a map published by the Bureau of Agricul- tural Economics representing the distribution of Florida grapefruit in the 1932-33 season. The figures accompanying the circles add greatly to the clarity of the presentation. The circles alone, due to the difficulty of comparing circular areas, do not convey a clear impression of the dif- ference in the amounts. For example, the circles in Illinois and Ohio appear to be nearly the same size, yet the figure for Ohio exceeds that for Illinois by 40 percent. Objections to the use of circles for extended series in map charts are the length of time required for the calculation of the diameters and the close plotting of minute differences in size. Even employing the short- cut method described in Chapter VII, the various steps that must be gone through to compute the diameters of circles for forty-eight States consume several hours of time. The plotting and inking of forty-eight circles, if accurately done, takes at least as long. When the ineffective- ness of circles for comparisons of size is added, there is not much to be said in favor of their use in map charts containing a considerable num- ber of geographical units. The difference in the size of the States presents a problem in draft- ing United States map charts if the data are to be shown with circles. In most economic distributions the numbers for the New England and contiguous States are likely to be large. A circle which in the States of the South or West may be a mere dot has to be made so large in the lower New England States that it blots out all other details. Frequently the circles for Rhode Island, Connecticut, and Delaware must be placed at the right of the chart, outside the State boundaries. MAPS WITH COLUMNS, BARS, OR CURVES On map charts comparisons of size in the form of columns are diffi- STATISTICAL MAP CHARTS 109 Figures indicate number of cars U.S. Department of Agriculture CHART 86. DISTRIBUTION OF FLORIDA GRAPEFRUIT IN THE 1932-33 SEASON. cult to interpret, due to the lack of a common base. Time series shown as curves, columns, or bars are open to the same objection. They com- plicate the chart by presenting too many types of comparisons at the same time. The primary purpose of a statistical map chart is to show two things : geographical location and differences in size. The inclusion 110 GRAPHIC PRESENTATION SIMPLIFIED of additional aspects of the data, difficult to read and compare, tends to obscure a clear impression of the main objective of the chart. PIN AND TACK MAPS Geographical distributions on wall maps may be shown by means of map tacks or pins of various forms or colors. Strings of beads or colored yarn may be employed for connecting lines or for curve effects. The facility this method offers for quickly making changes and adding new data makes it especially adapted for a continuing record of changing conditions. No skill or knowledge of drafting is needed for the prepara- tion and maintenance of such charts. Figure 2 illustrates some of the map tacks in current use. Series I 500 I The Most Common Size used is this spherical head pin. oo Series 600 For Congested Maps or charts and holding ter- ritory or route cord in place use this pin. Series! 5400 Glass Spot Pin . The spot is fused in the head of the pin. It cannot come off. Of Series I 5000 I Enamel Spot or "Ring Pin." Spot is enam- eled on the glass. This and the glass spot pin pho- tograph as a ring. Series 7000 Oil Well Pin. Shape resembles oil well der- rick. Can be supplied with two-colored head. Seriu550 Series4500 Map Ring. Colored celluloid ring for slip- ping over head of pin to indicate additional fact. Pins and Beads An An Un Dn Series Series! Series I Series! 6300 6100 I 6400 | 6200| Educational Exhibition Company, Inc. FIGURE 2. MAP TACKS FOR LARGE MAP CHARTS. STATISTICAL MAP CHARTS III FLOW MAPS This designation covers an extensive variety of designs and purposes. Some types, such as traffic maps, show direction of movement with con- necting lines. Both direction and volume may be shown by thickening the portions of the line or curve representing heavy volume of traffic or by repeating the curve in parallel or converging lines. The latter method is frequently used for charting ocean routes of travel or commerce. Map charts in which certain localities, cities, or centers of distribution are connected with other points on the map by single straight or curved lines to show a particular relationship are also classed as flow maps. Many of these types are simple in design and in drafting. Those in which the thickness of the curve or line represents varying magnitudes of the data are difficult to plot accurately, as the variations on such a small scale are necessarily minute. KEYS Nearly all map charts require the addition of keys to identify the colors or shadings in the chart. If the distribution of the data by size is markedly irregular, the selection of categories may have to be made without much regard for uniform gradation in amounts. The number of keys should be kept down, if possible, to not more than five or six. X PICTORIAL CHARTS tHE value of pictorial charts for presenting statistical facts depends chiefly on how and for whom they are used. They are well suited for illustrations in newspapers and magazines and for any type of audience requiring novelty in form of presentation to attract attention and interest. The use of pictorial figures does not give the best results, as a rule, in charts prepared for business - or professional men, who generally prefer the simpler conventional types of design, without ornamental or pictorial trim- mings. Pictorial charts may be used effectively, if they are accurately drawn, in showing simple comparispns of size. However, many pub- lished pictorial comparisons representing the human figure are mis- leading, due to the fact that in the drafting only one dimension, that of height, is taken into account, while the impression received by the observer is that of volume or bulk. Drawings of this kind, based on a single dimension, always exaggerate the difference between the numbers compared. 112 PICTORIAL CHARTS 113 BAR PICTORIAL CHARTS A bar pictorial design frequently used is made up of rows of small figures or symbols equal in size, each representing a stated number of units. The chief problem in planning a chart of this type is the selec- tion of figures or symbols sufficiently representative of the components to make the association obvious to the observer. Otherwise they are less effective than the ordinary rectangular-bar designs. Examples as far-fetched as a spool of thread to represent the textile industry or an ax for the lumber industry are occasionally seen. Chart 87, representing the employee distribution in a large tele- phone company, is an example of the bar pictorial type. The figures in each bar suggest the type of occupation designated in the stub. NUMBER OF EMPLOYEES MALE PLANT CRAFTSMEN FEMALE TRAFFIC OPERATING CLERICAL ALL OTHER tttttitiiitl iimiminmt 1 1 II I II! . EACH SYMBOL REPRESENTS IOOO EMPLOYEES. American Telephone and Telegraph Company CHART 87. TYPICAL DISTRIBUTION OF EMPLOYEES IN A LARGE TELEPHONE COMPANY. A large variety of pictorial symbols printed in sheets may be ob- tained from firms engaged in the production of material for this type of graphic presentation. A few samples are shown in Chart 88. Charts representing industrial data are sometimes made of small drawings of machinery, materials, or products. If special designs are required, they 114 GRAPHIC PRESENTATION SIMPLIFIED should be drawn oversize and reduced photographically for duplica- tion by photostat or offset printing. r//////A The Pictograph Corporation CHART 88. PRINTED SYMBOLS FOR USE IN BAR PICTORIAL CHARTS. Both the advantages and the disadvantages of the pictorial method are illustrated in Chart 89. The chart was copied from the first quar- terly report of the War Assets Administration in 1946. It is unquestion- ably much more striking in appearance than a plain bar chart of the same data would be. The pictorial figures for "Plants and Plant Sites" and "Aircraft" probably aid the reader to some extent in visualizing these components. It is doubtful whether the others add anything to the presentation. An undershirt is hardly representative of the thou- sands of miscellaneous items listed as consumer goods, nor a motor of the huge variety of surplus capital and producer goods. a s-l 3 o o co 5 I m > -< O 8 O CO O TJ m 3J 115 XI MISCELLANEOUS TYPES i HE types of design described in the preceding chapters comprise those that are most commonly used for the graphic presentation of statistical facts. The examples dis- cussed in this chapter include a number" of variations and adaptations of the basic types, employed to bring out clearly special aspects of the subject-matter. RANKING CHARTS Charts 90 and 91 present two methods for comparing series in which the components are arranged by order of their rank in a com- mon attribute. In Chart 90 a number of commodity groups are ranked at two different periods on the basis of wholesale-price levels. In the first column the groups are ranked on the monthly average in 1939, and in the second, on the price level in December, 1945. The change between the two periods is indicated by the connecting dash lines. This method is effective with short series, but if the chart includes a 116 MISCELLANEOUS TYPES 117 1939 RANK AVERAGE 1945 DECEMBER RANK 2. 4. 5. 6. 8. Hides and leather products X N j V""'-' - \ /> \ / \ 1 \ \/ ^ a %. ' x / V v . A Farm products 1. Metals and metal products Building materials 2. 3. 4. Building materials Hides and leather products House furnishing goods Foods Chemicals and allied products . \/ A \ >x' Metals and metal products 5. 6. 7. 8. 9. 10. \ / /V Miscellaneous > t' x \ y House furnishing goods \ A Y/ \ \ / * \ s \ / / \ \ S A / \ ^ / \t \ s \ Fuel and lighting Textile products Foods / /v\ ^ /v\ \ K V V Chemicals and allied products Textile products x-r \ \ / \ Miscellaneous N Farm products Fuel and lighting 10. CHART 90. RANK OF COMMODITY GROUPS BASED ON WHOLESALE PRICES: 1939 AVERAGE AND DECEMBER, 1945. large number of components, the criss-crossing lines become too con- fusing for easy reading. In Chart 91 the States are arranged in order of total ranking in ten educational features. The range in each feature for the whole country 118 GRAPHIC PRESENTATION SIMPLIFIED 1 WASHINGTON 2 MASSACHUSETTS 3 NEWM3RK 4 CALIFORNIA 5 CONNECTICUT b OHIO 7 NtW JERSEY 8 ILLINOIS 9 COLORADO (Q INDIANA I \ RHODE, I5LAND 12 VERMONT 15 WW HAMPSHIRE 14 UTAH 15 OREGON 16 MONTANA 17 MICHIGAN 18 N DAKOTA 19 IDAHO CQ MINNESOTA i\ IOWA 12- MAINE. 3 PENNSYLVANIA tA KANSAS 5 NEBRASKA ZO 5. DAKOTA & NEVADA ea VMCONSIN 9 WYOMING 30 ARIZONA 31 OKLAHOMA x MISSOURI 33 W VIRGINIA 34 FLORIDA 35 DELAWARE 56 MARYLAND 37 TEIMNE55LE 58 TEXAS 39 LOUISIANA 40 NEW MEXICO 41 VIRGINIA 42 KENTUCKY 43 ARKANSAS 44 GEORGIA 45 MIS\S3\Ppl 46 N CAROLINA 4? v> CAROLINA 46 ALABAMA CHART 91. RANK OF EACH OF THE UNITED STATES IN TEN EDUCATIONAL FEATURES: 1910. FROM GREENWICH EDUCATIONAL SURVEY. MISCELLANEOUS TYPES 119 was first determined. If a State ranked in the upper 25 percent of this range, it was represented by a white oblong, if in the next 25 percent, by a light diagonal shading, if in the third, by a darker shading, and if in the lowest group, by a solid black oblong. This method of classification placed Washington at the head of the list of States, with only one feature rated below the upper 25 percent. Alabama came last, its ratings in all ten features falling within the lowest percentage group. FREQUENCY-DISTRIBUTION CHARTS The planning and drafting of frequency-distribution charts follow closely the methods employed in charting time series in curve and column designs. The chief difference is that the horizontal scale repre- sents categories of size, value, or some other attribute, instead of periods of time. If the basic units are too numerous for individual plot- ting, they are grouped in class intervals. This method is illustrated by Chart 92, in which each unit of the scale represents a class interval of five years. MILLIONS 15 12 k iiiiiiiiiiiijli iiiiiiiiii AGE Under 5- 10- 15- 20- 25- 30- 35- 40- 45- 50- 55- 60- 65- 70- 75- 5 9 14 19 24 29 34 39 44 49 54 59 64 69 74 Over CHART 92. ESTIMATED POPULATION, UNITED STATES, BY AGE GROUPS: 1945. 120 GRAPHIC PRESENTATION SIMPLIFIED The curve design is generally employed for frequency distribu- tions of long series which require close plotting. The use of columns for short series is illustrated in Chart 93. The data are estimates by the Census Bureau of the weekly hours worked during the third quar- ter of 1945 by employees fourteen years old and over in non-agricul- tural occupations. The horizontal scale represents the categories of hours worked, and the columns the number of employees in each category. The zero base should not be omitted from the amount scale in charts of this type. The horizontal scale may begin at any point selected as the first unit or class interval of the range covered by the series. $10.74 \2.8\$ ( MILLIONS OF EMPLOYEES ) Hours 30-39 40-44 45-49 50-54 55-59 60 or more CHART 93. ESTIMATED WEEKLY HOURS WORKED, NON-AGRICULTURAL EMPLOYMENT: THIRD QUARTER, 1945. RELATIVE-VARIATION CHARTS A type of chart which was used extensively during the last war for comparing monthly fluctuations of stocks and procurement of equipment and supplies is illustrated in Charts 94 and 95. The grids MISCELLANEOUS TYPES 121 of the components in Chart 94 are equal in size. In all of them the highest amount of the monthly series was plotted at exactly the same distance below the upper line of the grid. The amount scales were then adjusted to this measure and the remaining points of the curves plotted to the adjusted scales. For example, the highest figure of stocks in the first item of Chart 94, "Blankets, Wool, OD, M-1934," was 5,936,000, reached in February. This high point was plotted one eighth of an inch below the upper grid line. In the second chart, "Cutter, Wire, M-1938," the high point for the year was 85,000, which was reached in October. This amount was plotted at the same height above the base as the maximum variation in the first chart. The same procedure was followed with the other equipment items. In all of them the high point of the series occupies the same vertical position. BLANKET, WOOL, 00, M-1934 CUTTER, WIRE, M-1938 CAN,, MEAT Mill ions KNIFE, M-1926 Mill ions iiiiiiiiiiiiiiliiilliiiiiiliiiiii M A J A SO NO J F AM J J AS N D CHART 94. RELATIVE MONTHLY VARIATION STOCKS, SELECTED EQUIP- MENT ITEMS: 1944. FROM Statistical Yearbook, QUARTERMASTER CORPS. 122 FLOUR, WHEAT, WHITE GRAPHIC PRESENTATION SIMPLIFIED PEACHES, CANNED 500 77T? - 100 Tr^r _ - 400 W.-.Y/ - 75 - - 300 11 ^ Him 50 - Xvjvi 200 Us ' ;;:::: : : ' : : : : : :v 100 ?f~:.: 81 25 -v.Xv 11 Xl3 , , P-JB HASH, MEAT AND VEGETABLE, CANNED PINEAPPLE, CANNED 15 - 10 60 - 20 J JF MAM JJAS ON D JFM AMJ JA SOND CHART 95. RELATIVE MONTHLY VARIATION NON-PERISHABLE SUBSIS- TENCE PLACED ON CONTRACT, SELECTED ITEMS: 1944. FROM Statistical Yearbook, QUARTERMASTER CORPS. Chart 95 shows the same type of comparison in a column design. It represents the quantity, in millions of pounds, of various non-perish- able subsistence items placed on contract each month in 1943. The highest columns in all the charts are exactly the same height, although the quantities they represent range from 13 million to 479 million pounds. These examples were copied from printed sheets 7/2-by-lOM inches in size, each containing twelve charts. They are quite as effective for comparing relative changes in series of different magnitudes as the rate-of-change type of design and are more easily understood. Com- pared with the employment of percentages or index numbers, this method has the advantage that it obviates the necessity for conversion of the basic data to relative numbers. MISCELLANEOUS TYPES 123 ORGANIZATION CHARTS Distributions of functions and personnel may be shown graphically in a wide variety of designs. Chart 96, representing a theoretical dis- tribution of executive and administrative functions in an industrial corporation, is an example of the type frequently employed for this purpose. The chart units may be represented by oblongs or circles. Oblongs are generally preferred if names of personnel are to be lettered within the units. Colored inks may be used to differentiate various types of functions, the units grading from a strong color for the higher execu- tive positions to lighter tints or colors for the minor units. CHART 96. TYPICAL ORGANIZATION-CHART DESIGN. COMPARISON OF EQUAL AMOUNTS WITH CIRCLES Chart 97 is an example of the employment of circles for the com- 124 GRAPHIC PRESENTATION SIMPLIFIED THE DEFICIT IN PERSPECTIVE COMPARISON OF FEDERAL GOVERNMENT EXPENDITURES AND DEFICITS, FISCAL YEARS DEFICIT 2 MONTHS, JULY AND AUGUST, 1936 EXPENDITURES i YEAR, AVERAGE, 1900-1913 DEFICIT i YEAR, ESTIMATE, 1939 DEFICIT 9 YEARS, TOTAL, 1931-1939 FROM 178 9 TO 1642, FISCAL YEARS ENDED ON DECE MBER 31; FROM 18*4 TO OATE.ON JUNE 30. SOURCE ' UNITED STATES TREASURY DEPARTMENT. National Industrial Conference Board CHART 97. MISCELLANEOUS TYPES 125 parison of amounts which are approximately equal in size but which differ inherently in a given attribute. The upper and lower circles in the first chart represent respectively the Federal deficit for two months in 1938 and the average yearly expenditures from 1900 to 1913. The second chart is a similar comparison of the estimated deficit in 1939 with the total expenditures over the 76-year period from 1789 to 1864. The third chart compares the total deficit for the nine years from 1931 to 1939 with the total expenditures over a period of 125 years, 1789 to 1913. CIRCULAR-BAR DESIGN In Chart 98 a circular arrangement of the bars representing the values is substituted for the vertical sequence usually employed in bar CHART 98. EXPORTS, U.S. MERCHANDISE, AS PERCENT OF TOTAL EXPORT- ABLE GOODS: 1909 TO 1945. 126 GRAPHIC PRESENTATION SIMPLIFIED charts. The percent figures lettered on each bar show the proportion of total exportable goods represented by American exports of mer- chandise at various periods from 1909 to 1945. Apart from its pictorial quality, this design offers little if any advan- tage to the reader over the conventional bar arrangement. It is not as easy to read and understand. However, striking variations from the stan- dard forms, of this or other types, are sometimes desirable in charts for publication in newspapers and popular magazines, where novelty in design is required to catch the attention of the casual reader. They should be limited to a single aspect of the data, and are usually not adapted for presentations involving the use of more than one pattern of shading or color. .XII ELEMENTARY TRAINING METHODS ft i HE preceding chapters describe the main types of design employed in statistical charts. The remain- ing chapters are devoted to suggestions and instruction for readers who may be interested in preparation for work of this character. The simple course outlined in this and the following two chapters was planned for beginners who have had no experience in designing or drafting statistical charts. Special emphasis is placed on study and practice in planning, lay-out, and plotting methods. Manual skill in the use of drafting instruments, although essential, is secondary to a thor- ough understanding of these fundamental procedures. The use of ink should be postponed until a fair degree of proficiency is reached in designing and plotting charts in pencil. A start can be made with no other equipment than a supply of printed graph paper, an ordinary ruler, and a typewriter. Practice with ruled forms affords a means for acquiring some knowledge of elemen- tary principles without the complication of handling unfamiliar draft- ing instruments at the same time. 127 128 GRAPHIC PRESENTATION SIMPLIFIED CHARTS ON PRINTED GRAPH PAPER Printed graph paper can be obtained in a variety of rulings. Samples of five different rulings are shown in Figure 3. Of these, the most use- ful for chart purposes are the 5 and 10 per inch. The 6 ruling corre- sponds to vertical typewriter spaces, and the 12 and 10 to horizontal spaces of elite and pica type. In Chart 99 the grid ruling and curve plotting were done before the typing of the title and scales. The time scale covers 12 years, but, as the plotting is to line, the grid lay-out covers only 11 spaces. The ruling of the graph paper is 5 to the inch. Allowing 2 rulings per space, the grid measures 22 fifths or 4% inches wide. The amount scale, at 1 vertical space per billion dollars, takes almost 13 spaces, but, in order to keep the scale in multiples of 5 and leave some space above the highest plotting, it was extended to 15 fifths or 3 inches. The curve and grid lines were drawn with ruler and pencil. CHART 99. ELEMENTARY TRAINING METHODS 129 SUBDIVISIONS PER INCH 6 8 10 12 Codex Company. Inc. FIGURE 3. SAMPLES OF GRAPH-PAPER RULING. 130 GRAPHIC PRESENTATION SIMPLIFIED After the grid ruling and curve plotting were finished, the title and scales were lettered on the typewriter. Special care must be taken with typewritten lettering to secure exact centering of time- and amount- scale numbers to the corresponding rulings. In multicurve charts effective contrast can be obtained by using dif- ferent colored pencils for drafting the curves. Graph paper in light-blue EMPLOYMENT OF WOMEN SELECTED DURABLE GOODS INDUSTRIES 0000 CCT Percent of Wage-Earners 10 20 30 1*0 IRON & STEEL & THEIR PRODUCTS 7.1 0000000 11.2 mm- ELECTRICAL MACHINERY MACHINERY 5.6 (EXCEPT ELECTRICAL) 93 TRANSPORTATION EQUIP. 1,1 (EXCEPT AUTOMOBILES) 10.5 NONFERROUS METALS & 172 THEIR PRODUCTS 16.5 LUMBER & TIMBER BASIC PRODUCTS 1.7 5.2 FURNITURE & FINISHED 9.1 1)0000 LUMBER PRODUCTS ik.k $m ALL DURABLE GOODS INDUSTRIES War Manpower Commission CHART 100. ELEMENTARY TRAINING METHODS 131 ruling is best if the charts are intended for photostat or printed repro- duction. The ruled background in this color will not show in photostat negatives or printing plates. Drafting of bar and column charts on graph paper is equally simple. With the variety of rulings available, any combination of bars and spaces can be worked out with little difficulty. TYPEWRITTEN CHARTS Chart 100 is an example of a bar chart done entirely on the typewriter. All of this chart was made without removing the paper from the machine. The vertical spacing is in single and double space. Each bar is plotted by striking the appropriate key as many times as there are units in the figure at the left of the bar. The title is in spaced capitals underlined, the subtitle in underlined capitals. The key for identifying the symbols in the bars is placed imme- diately below the subtitle. The upper bar of each pair is made of super- imposed parentheses, and the lower bar of the number sign. The dollar sign is sometimes used in typewritten bar charts, if the values are in money. The bars represent rounded numbers. Rounding is necessary in type- written charts, as each symbol stands for a complete unit. In the item "Electrical Machinery," for example, the 1941 figure, 30.1, is rounded to 30 symbols and the 1942 figure, 33.7, raised to 34. Column and curve designs take more time and care than the bar type. The vertical plotting required in typed column charts involves backspacing for each unit in the columns. Curve charts present dif- ficult problems in plotting, and the vertical ruling for the grids, unless the charts are very small, can be done only on a long-carriage machine. X SMALL CHARTS ON UNRULED PAPER HE next step involves the draft- ing of small charts on unruled paper, without the aid of typewriter spacing or printed ruling. A thorough understanding of the methods employed in planning, grid ruling, and plotting of such charts is of the greatest importance, as they will be used constantly in all future work. EQUIPMENT The additional equipment needed comprises a drawing board, a T-square, two triangles, and a ruling pen. A drawing board about 12-by-17 inches will be large enough. The wood should be of good quality. It is important that the ends and sides be exactly parallel. The T-square should be 15 to 18 inches long, with transparent edges. Two triangles of transparent material, one 4" 90 and one 6" 30, will be required. A small French curve for drawing curved lines, although seldom used, may be added. Larger equipment will be needed for 132 SMALL CHARTS ON UNRULED PAPER 133 work on charts of display size, but is awkward and inconvenient to handle in drafting small charts. GRID LAY-OUT The instructions and examples that follow apply to the lay-out in pencil, which should be done before the drafting in ink is begun. The initial problem, and the one which usually stumps the begin- ner, is how to lay out the grid ruling for the scales in curve charts and the bars and spacing in bar and column charts. Assume, as a simple example, that the grid of a curve chart 5 inches wide is SON CHART 101. USE OF SCALE IN GRID LAY-OUT. 134 GRAPHIC PRESENTATION SIMPLIFIED to be ruled for a time scale of 12 months, thus requiring 12 spaces for the curve plotting. How is the width of the spaces to be deter- mined? One can, of course, divide 5 by 12, but the quotient, 0.41666 and so on to infinity, is not a practicable unit for drafting. A little elemen- tary geometry will solve the problem quickly and more accurately than any amount of arithmetical calculation. Place diagonally across the grid any measure containing 12 equal spaces that is slightly longer than 5 inches. Adjust the angle until the first and last lines or gradua- tions coincide with the outside vertical lines of the grid. Mark the sub- divisions with pencil dots and rule with T-square or triangle. The method is illustrated in Chart 101, page 133. Any measure with equal spacing will serve, ruled correspondence paper, an ordinary foot rule, or printed graph paper. TYPES OF SCALES The triangular decimal scale shown in Figure 4 is commonly used by draftsmen for lay-out and plotting. It has six scales, with graduations ranging from 10 to 60 to the inch. Usually one of these will fit the data. If not, multiples of the required number of spaces on one of the scales can be used. Keuffel and Esser Co. FIGURE 4. TRIANGULAR DECIMAL SCALE. Lacking a scale of this type, a series of scales can be made from Figure 5 that will serve the purpose just as well or better. Each of these scales is six inches long. The first has 10 graduations to the inch and the succeeding three, 20, 30, and 40. The scales can be adapted for use in drafting and lay-out by copying the figures and graduations on tapes of tough paper or light cardboard, extending the length to about ten inches. This length will be sufficient until work on display charts is undertaken, when tapes two or three feet long may be needed. In some respects tapes have been found to be much more convenient = ro E OJ ^ 3 <n = Oi OB = 1 5 = o h M - O <n z OJ _ * = oi = "1 ^ ii _5 ""1 CM - <5 = ro = > * ~ o = ro = oi iz: ro ==. * 5 = 63 ' o _ M 135 136 GRAPHIC PRESENTATION SIMPLIFIED than the triangular scale. One objection to the latter is that it will not stay put. When used in scaling or plotting, it must be held in the required position, as it is apt to slide about on the chart, particularly if the drawing board is set at a convenient slant for drafting. With tapes, however, this tendency is obviated by securing each end of the scale with adhesive tape. This tape is backed with a light adhesive which permits removal of the scale without defacing the paper. It may be used also instead of thumb tacks for fastening the paper to the drawing board. Another advantage of tapes over scales of wood or metal is that they permit free movement of the T-square and triangles over the surface of the chart without disturbing the position of the scale. JOINED-BAR LAY-OUT The method for laying out the bars vertically is illustrated in Chart 102. The chart contains 5 bars. The scale is laid diagonally across the grid, with 5 on the upper line of the first bar and zero on the bottom line of the fifth bar. The subdivisions are noted from the scale and lined with T-square and pencil. CHART 102. VERTICAL DISTRIBUTION OF BARS. SMALL CHARTS ON UNRULED PAPER 137 CHART 103. METHOD FOR PLOTTING AMOUNTS. The method to be followed in the plotting of the various amounts is pictured in Chart 103. The series comprises the following numbers, arranged in descending order: Bar First Second Third Fourth Fifth Amount 645 520 423 255 146 The longest bar represents 645. The scale is placed at 7, the equiva- lent of 700, on the right edge of the grid, with zero on the base line of the bars. The chart shows the use of the triangle for plotting the amounts. If a scale is used instead of lettered figures on the bars, it can be laid out by the same method employed for plotting the length of the bars. 138 GRAPHIC PRESENTATION SIMPLIFIED BAR SPACE BAR CHART 104. BARS AND SPACING IN SPACED-BAR CHARTS. SPACED-BAR LAY-OUT Chart 104 shows the method for laying out the bars and spaces in a spaced-bar design. The spaces are one-half wider than the bars. There are 5 bars and 4 spaces, which, at 4 graduations for the bars and 6 for the spaces, total 44 graduations. The scale is placed at 44 on the upper line of the first bar, with zero on the lower line of the fifth bar. The method for plotting the amounts is the same as that used in joined-bar charts. COLUMN-CHART LAY-OUT Chart 105 shows a spaced-column lay-out in which the spaces are one half the width of the columns. Each month, with the excep- tion of the last, which is not followed by a space, represents 3 graduations, 2 for the column and 1 for the space, or a total of 35 in all. Joined-column charts are laid out in the same way as joined-bar SMALL CHARTS ON UNRULED PAPER 139 JFMAMJ JASOND CHART 105. COLUMNS AND SPACING IN SP AGED-COLUMN CHARTS. MAMJJASOND CHART 106. PLOTTING OF AMOUNTS ON COLUMN CHARTS. 140 GRAPHIC PRESENTATION SIMPLIFIED 20 10 MAMJJASOND CHART 107. CURVE-CHART LAY-OUT. charts. The only difference is that the scale is horizontal instead of vertical. Plotting of the amounts is illustrated in Chart 106, on page 139. The figure for the highest column is 54. The scale is set at 60 on the upper line of the grid to allow room for lettering the figures, if these are placed above the columns. In any case some blank space should be left above the highest column. This is true also in the case of bar charts and curve charts, where some space should be left after the longest bar and above the highest point of the curve, unless it is broken. CURVE-CHART LAY-OUT AND PLOTTING The vertical ruling of the grid in Chart 107 is done in the same way as in Chart 101, page 133, except that, as the plotting is to line, there are 11 instead of 12 spaces. The curve represents the same series of numbers that was used in the spaced-column example and is plotted in the same way. SMALL CHARTS ON UNRULED PAPER 141 946 523 CHART 108. CIRCLE- AND SECTOR-CHART LAY-OUT. CIRCLE- AND SECTOR-CHART LAY-OUT Chart 108 shows a comparison of the numbers 946 and 523 drafted as circles proportional in area. The first circle is subdivided in four, and the second in three percentage sectors. The first step is to determine the diameters of the circles. Assuming a diameter of 4 inches for the larger circle, the diameter of the smaller one, calculated by the method described in Chapter VII, will be 2.96 inches (square root of the quotient of 523 divided by 946, multiplied by 4 inches ) . A compass will be needed for drawing the circles^, and a protractor for pointing off the sectors. (See Figure 6, page 142.) A cheap compass, obtainable in any drafting-supply store, will serve for pencil sketching. For use with ink a better instrument, with pen attach- ment and lengthening bar, will be required. Percentage protractors are generally preferred for statistical drafting to those graduated in degrees. A numerical series can be more easily converted to percents than to degrees of a circle. The protractor is laid over the circle and the percents corresponding to each sector pointed off on the circumference. The order of plotting is by size of sectors, the largest first, the next largest second, and so on. Sectors representing a "Miscellaneous" or "All Other" group of com- 142 GRAPHIC PRESENTATION SIMPLIFIED ponents are placed last in the series of sectors. The plotting begins at the center of the upper hemisphere and continues clockwise from right to left. Familiarity with methods of lay-out and speed in their application are the first requirements in the drafting of statistical charts. The methods illustrated in the preceding examples are simple, but consid- Keuffel and Esser Co. FIGURE 6. COMPASS AND PROTRACTOR. erable practice will be needed to get them clearly in mind so they can be applied easily and quickly. The beginner is advised to repeat the examples for the different types a number of times, changing each time the dimensions of the grids, the numerical series, and the distribu- tion of spacing in bar and column designs, so as to become thoroughly familiar with the respective procedures. SMALL CHARTS ON UNRULED PAPER 143 LETTERING Typewritten lettering should be used unless a lettering guide is avail- able. Hand-lettering on small charts is too slow and usually is less satisfactory than typewriting. The machine must give a firm impression and good alignment. The large open elite type is preferable to pica and larger sizes. Carbon ribbons give clear black copy, but the lettering is apt to smudge if the chart undergoes much handling. The Vari-Typer machine is used extensively for lettering small charts. It has a number of styles and sizes of interchangeable type. The quality of the work is superior to typewriting, but operation of the machine requires trained personnel. If the .chart is intended for printed reproduction, cut-out letters can be used for the title. These are backed with an adhesive and can be removed and re-used. The titles for Charts 10 and 12 and a num- ber of others reproduced in the preceding chapters were made of cut-out letters. Ralph C. Coxhead Corporation FIGURE 7. THE VARI-TYPER. PAPER Paper for chart purposes should be strong, of uniform thickness, and usable on both sides. It can be either smooth or medium, and single or double thickness. Bond papers of good quality and smooth finish and heavy-weight unruled ledger papers of standard size are extensively used. 144 GRAPHIC PRESENTATION SIMPLIFIED INKING After the ruling and plotting are completed, the pencil sketch may be lined in India ink with a ruling pen. This instrument is perhaps the most useful and the most used in the draftsman's kit. About four fifths of all the drafting on statistical charts, outside the lettering, is done with the ruling pen. Skill in its use can be acquired only through prac- tice. Some suggestions worth keeping in mind are: that no ink be left on the outside of the pen after filling; that the supply of ink in the pen be kept uniform; that the edge of the pen be kept exactly parallel with the guiding edge; and, of special importance, that the pen be kept thoroughly clean. Dirty pens do dirty work, and ink left on the pen when it is not in use is likely to corrode the metal. Keuffel and Esser Co. FIGURE 8. RULING PEN. Various types of ruling pens, such as dotting and railroad pens, used for special purposes, are seldom needed in the drafting of statistical charts. Designs containing a large number of small circles, of which the circle map is an example, are usually ineffective for com- parisons of size, but, if such designs are required, a small bow pen and a drop pen for filling in the circles will be needed. For such close work the six-inch compass commonly used for circle charts of display size is too large. Until such time as the beginner has had sufficient practice in methods of lay-out and plotting to apply them accurately and without hesitation, the drawing should be completed in pencil and carefully checked with the data worksheet before the inking is begun. The pencil sketch serves as a guide for the ruling pen, thus leaving the attention free for the inking process, where a slip or an error is likely to end in a difficult and unsightly erasing job. Mistakes in pencil can be easily corrected, but once they are inked in they are frequently irremediable. In many cases the entire chart may have to be redone. SMALL CHARTS ON UNRULED PAPER 145 Keuffel and Esser Co. FIGURE 9. Bow AND DROP PENS. ORDER OF OPERATIONS The following order of operations if faithfully adhered to will save time and help to insure accuracy: 1. Lay out and plot in pencil 2. Check with worksheet of data 3. Ink with ruling pen 4. Clean off with artgum any traces remaining of pencil sketch 5. Lettering 6. Check lettering with worksheet 7. Apply shading or color 8. Inspect and clean XIV DISPLAY CHARTS ISPLAY charts differ in some respects from the smaller sizes in principles of construction. The latter are usually read at a distance of around two to four feet. The smallest lettering on a display chart must be clearly legible at several times this distance. If the chart is for use in a large conference or hearing, all details should be easily read at not less than twenty feet from the chart. Because of the purposes for which display charts are used, greater emphasis on simplicity of design and the elimination of surplus word- age is required. Unlike the small chart, which is generally viewed under conditions that give opportunity for study, the display chart, if for use in meetings and conferences, must get its message across in much less time. Titles and stubs should be carefully edited to reduce the amount of lettering. Long titles and subtitles occupy too much space and throw the chart out of balance. As a rule, not more than two aspects of the data can be effectively presented on a single chart. If it is not feasible to cover the subject in one chart without crowding, it should be broken 146 DISPLAY CHARTS 147 down into two or more. Three simple charts are better than one com- plicated one. USE OF COLOR One of the most significant developments in design and drafting technique is the marked increase in the employment of color in all types of statistical charts. Willard Brinton's comment in his Graphic Presentation, published in 1939, summarizes the views generally held by specialists in chart design: "It is believed that the evidence is con- clusive that to get the maximum results in graphic presentation the question is not 'Can one afford to use color?' but 'Can one afford to omit color?' " A major contribution to this development has been the adhesive color material introduced a few years ago. Apart from its superiority to colored inks, paints, and washes in ease and speed of application, it has the advantage that the colors can be quickly removed and replaced, if corrections or changes have to be made, without defacing or injuring the surface of the chart. In addition to its use for filling in surfaces with color or shading, this adhesive material may be employed in the form of tapes or narrow strips in substitution for inked curve patterns in display charts. The tapes come in widths from one-eighth inch to one inch. The half -inch and quarter-inch widths are frequently used for outlining regional subdivisions on maps. The presentation of colored display charts in conferences or meetings sometimes results in requests for a number of small photostat or printed black-on-white copies. If the colors are in paint or water colors, the charts will have to be done over in black for reproduction. If adhesive colors are used, they can be removed and replaced with black shadings. After the printed or photostat copies are made, these in turn, can be taken off and replaced with the original colors. The two operations will ordinarily take, on a single chart, no more than an hour or so, against probably a day's work to make the whole chart over. LAY-OUT AND EQUIPMENT The methods and procedures described in the preceding chapter with relation to lay-out and plotting of small charts apply equally to those of display size. A drafting table, adjustable for height and slant, 148 GRAPHIC PRESENTATION SIMPLIFIED FIGURE 10. DRAFTING TABLE FITTED WITH PARALLEL RULE. will be needed. A desirable addition is the parallel rule illustrated in Figure 10. This device automatically maintains the rule at right angles to the^ sides of the table. Other items which will be required are larger triangles, longer scales or tapes, and larger ruling and lettering pens. Display charts are generally drafted on illustration board from 20-by- 30 to 30-by-40 inches in size. The stock should be heavy enough so that it will not curl or bend. Highly glazed surfaces which reflect the light should not be used. Samples of different boards should be tested to see whether they are suitable for drafting. Some are finished with a chalky substance that clogs the pens, and in others the direction of the grain is a source of difficulty in drafting. LETTERING Lettering on display charts is usually done with lettering guides. Figure 11 gives some idea of the design and method of operation of a well-known type. In operation the pen in the forward arm of the scriber is guided by the template grooved with the letters and figures. The height of the lettering ranges from .08 to 2 inches. If equipment for lettering with guides is lacking, the beginner may have to start with hand-lettering, although if he remains in this type of DISPLAY CHARTS 149 Keuffel and Esser Co. FIGURE 11. LEROY LETTERING GUIDE. work it is likely that he will eventually graduate to the use of guides. For this reason it will be advisable to practice some of the styles of lettering commonly employed on display charts lettered with guides. Early efforts had best be limited to capitals. Small letters are more difficult, and in the majority of display charts only capitals are used. A sample alphabet is shown in Figure 12, page 150. The relation of width to height and the spacing between letters are the chief problems 'in hand-lettering. All lettering should be laid out in pencil before inking. Large letters may be outlined in pencil with stencils or cut-out letters and afterward filled in with ink. In this way uniformity is secured, with less chance of the slips and mistakes which are likely to occur if the draftsman depends entirely on his own un- aided judgment and skill. Little time or practice should be devoted to ornate and fancy types of lettering. They are sometimes used in statis- tical charts to emphasize a word or words in the title, but the same effect can be obtained by underlining. PAINTS Poster paints are the best color medium for paper or cloth rolled charts. The products of different manufacturers vary to some extent in adaptability for this purpose, and samples of the various makes should ISO GRAPHIC PRESENTATION SIMPLIFIED ABCDEFGH IJKLMNOP QRSTUVW XYZ abcdefghijk Imnopqrstu vwxyz 01234567 89 FIGURE 12. SAMPLE LETTERING-GUIDE ALPHABET. DISPLAY CHARTS 151 be tested to insure that one is chosen which will leave a brilliant, smooth surface free from brush marks. For stiff surfaces, as has been pointed out, the adhesive colors are far superior in appearance and are much easier to apply. CRAYONS Crayons are little used for filling in surfaces on illustration board. They are easier to use than paints on rolled charts but do not afford as striking contrasts. They are applied with light parallel strokes. The color may be deepened by repeating the application. The lines left by the strokes of the crayon may be smoothed by rubbing the surface lightly with a cloth. AIRBRUSH COLORING The airbrush can be employed effectively in tinting large maps, but is seldom used for coloring statistical display charts. All parts of the chart not to be colored must be masked out with paper, and this must be secured with adhesive pressed down firmly on the chart to prevent the color from creeping under the edges. After the color is applied the masking is removed. The whole operation takes much longer than is usually required with adhesive colors or paints. If the chart is in several colors, the process becomes extremely complicated and time-consuming. ROLLED CHARTS Display charts light in weight which can be rolled tightly to occupy a small amount of space (for shipment by mail or express or to be carried as luggage) can be made of tough paper or of cloth similar to that used for window shades. Color must be applied with ink, cray- ons, paints, or water-colors, as adhesive shadings become detached if charts are rolled. Rolled charts should be stiffened at top and bottom with light strips of wood ( "half-rounds," which can be obtained in any carpenter shop, are about the right weight), as illustrated in Figure 13, page 152, to prevent the chart from buckling or remaining partly unrolled when in use. The strips can be nailed on with short brads. For convenience in hanging, a short piece of cord or tape should be fastened to the upper strip. 152 GRAPHIC PRESENTATION SIMPLIFIED FIGURE 13. METHOD FOR STIFFENING ROLLED CHARTS. MOUNTING ON CARDBOARD Mounting paper charts on cardboard presents no problem where facilities for hot mounting under pressure are available, but these will be found only in large drafting installations. Mounting by hand is usually done with liquid rubber cement. This material will not shrink or warp the paper. It is sufficiently strong if a permanent mount is not required but loses its adhesive qualities with age. The cement is spread uniformly over the back of the chart and the paper pressed down firmly to make close contact with the cardboard. The chart should be smoothed carefully before the cement dries, to prevent wrinkling of the paper. XV REPRODUCTION PROCESSES I HE choice among the various methods employed for the reproduction of statistical charts depends mainly on the number of copies required. PHOTOSTAT If the number of copies needed does not exceed fifty, the photostat process is generally used. In this process the chart is copied photo- graphically on sensitized paper. A copy in white-on-black, called a "negative," is made, from which any number of black-on-white copies, called "positives," can be duplicated. Figure 14 pictures a half "nega- tive" and half "positive" photostatic copy. Copies made by this process can be obtained quickly and at moderate cost. The standard equipment will make enlargements up to 18-by-24 inches. If larger sizes are required, the prints may be made in sections and joined with adhesive. Charts in color cannot be reproduced by the photostat process. 153 154 GRAPHIC PRESENTATION SIMPLIFIED EDITORIAL OPTIMISM * ABOUT THE WAR M tr arshall f & i London Corr* I r gldor / 1 / acArthur / Air Raid / on Japan German Of f ens 1 ve Australia <y f 1942 APR MAY FIGURE 14. COMPARISON OF NEGATIVE AND POSITIVE PHOTOSTAT PRINTS. FROM Manual of Statistics, WAR DEPARTMENT, SOS. PHOTO-OFFSET In offset printing a sensitized zinc or aluminum plate is made from a photographic negative of the chart. On the press the ink adheres only to those parts of the plate that contain the image of the chart. In the printing process the inked image is transferred to a rubber roller and from this to the paper. The average plate can be used to make up to twenty-five or thirty thousand copies. As in all work for printed reproduction, special care should be taken in the preparation of the original charts, for the reason that any imper- fections, unless discovered on the negative, where they can be touched up, will be reproduced on the plate. Lithographers' artists are skilful in patching up defects on plates, but patching of this kind is expensive in cost and time. Excellent printing in from one to four colors can be done by this process, but, as each color requires a separate run through the press, color printing is much more expensive than black alone. Some of the best published work in colored statistical charts is printed by photo- offset. REPRODUCTION PROCESSES 155 MULTILITH In this process the chart is drawn directly on a thin aluminum plate. It saves the time required for the photographic process and eliminates the costly equipment for making photo-offset plates. From six to ten thousand copies can be obtained from a single plate. The image is usually not as clear as in printing done by photo-offset. STENCIL AND GELATIN DUPLICATORS For chart production with mimeograph stencils a special drawing board called the Mimeoscope is used together with various instru- ments designed for drafting on stencils. In reproduction by gelatin duplicators the original is typed or drawn with a methyl-violet dye and then transferred by contact, in reverse, to a strip of gelatin material from which the printing is done. These processes are convenient and efficient for duplication of re- ports, memoranda, releases, and tabulating forms, but are not very suit- able for satisfactory chart reproduction. The results obtained with them are not comparable in appearance with those secured with the photostat process and with multilith or photo-offset printing. ENLARGEMENTS Enlargement of small charts for printing is seldom done. Typewritten lettering if enlarged over 50 percent generally looks spotty and ragged. Slight differences in weight of lettering, due to uneven pressure in striking the keys of the typewriter, become prominently visible in the enlargement. Insignificant defects in the drawing that would not be noticeable in the original stand out clearly. Good enlargements to display size of carefully executed originals can be obtained by photography, but the cost is usually prohibitive. En- largements for display purposes made with the photostat cost less, but are much inferior in appearance. REDUCTIONS Charts for printed reproduction should be made large enough for a reduction of 20 to 50 percent. The reduction gives the chart a more 156 GRAPHIC PRESENTATION SIMPLIFIED finished appearance and eliminates minor irregularities in the drafting. The amount of reduction a chart will stand is governed chiefly by the size of the lettering. Figures 15a and 15b show various types of letter- ing and weights of ruling reduced one third and one half of the original size. Fine ruling is apt to show breaks or fade out entirely in reductions LETTER SIZES Slite Type - 12 characters per inch Pica Type - 10 characters per SMALL GOTHIC - 9 CHARACTER LARGE GOTHIC - 9 CHARACTER .120" TEMPLATE LETTERING .140" TEMPLATE LETTERING .175" TEMPLATE LETT .240" TEMPLATE LINE WEIGHTS 4 POINT ^-^^ 3 POINT 2'/2 POINT 2 POINT I !fe POINT I POINT 3/ 4 POINT 1/2 POINT Original Size Note: A point, in printer's measure, is approximately 1/12 of a pica, which, in turn is 1/6 of an inch. Therefore, a printer's point is approximately 1/72 inch. REPRODUCTION PROCESSES 157 of more than 50 percent. Reductions of elite typewritten lettering should not exceed 30 percent for printing on smooth paper or 20 percent for reproduction in newspapers. Reduction is calculated in terms of the linear dimensions of the chart, not of its area. A 50 percent reduction of a chart 10 inches wide by 14 inches long means that the width is reduced to 5 inches and the length to 7 inches. The reduction in area, of course, is much greater. In practice, instructions to the printer for reduction or enlargement are not expressed in fractions or percents. All that is necessary is to indi- cate on a line drawn parallel with one side of the chart the exact measure to which it is to be reduced or enlarged. A problem which frequently arises is to fit a chart into a given space in which the proportions of width and length differ from those of the chart. For example, suppose that a chart 8-by-15/2 inches is to be re- LETTER SIZES Elite Type - 12 characters per inch Pica Type - 10 characters per SMALL GOTHIC - 9 CHARACTER LARGE GOTHIC - 9 CHARACTER .120" TEMPLATE LETTERING .I4CTTEMPLATE LETTERING .175" TEMPLATE LET1 .240" TEMPLATE LINE WEIGHTS 4 POINT 3 POINT ^ 2^ POINT 2 POINT I '/ 2 POINT - I POINT - 3 POINT - ! / 2 POINT LETTER SIZES Klite Type - 12 character* pr inch Pica Type - 10 characters per SMALL GOTHIC - 9 CHARACTER LARGE GOTHIC - 9 CHARACTER .120" TEMPLATE LETTERING .140" TEMPLATE LETTERING .175" TEMPLATE LET! .240" TEMPLATE LINE WEIGHTS 4 POINT 3 POINT ^ 2'>*j POINT 2 POINT I '/ 2 POINT I POINT 3^ POINT 1/ POINT Reduced to two thirds of original Reduced to one half of original FIGURE 15A (OPPOSITE PAGE) AND FIGURE 15e (ABOVE). REDUCTION OF LETTERING AND RULING. FROM Time Series Charts, A Manual of Design and Construction. 158 GRAPHIC PRESENTATION SIMPLIFIED ESSENTIAL ITEMS Mask, Gaa, Training Mine, Land, Chemical 3,053,190 1,109,107 Same Size ESSENTIAL ITEMS Mask, Gaa, Training Mine, Land, Chemical 3,053,190 1,109,10? Reduction ESSENTIAL ITEMS Maak, Gas, Training Mine, Land, Chemical 3,053,190 1,109,10? 20% Reduction ESSENTIAL ITEMS Mask, Gaa, Training Mine, Land, Chemical 3,053,190 1,109,10? 30$ Reduction ESSENTIAL ITEMS Mask, Gas, Training Mine, Land, Chemical 3,053,190 40% 1,109,10? | Reduction ESSEHTIAL ITEMS Mask, Gaa, Training Mine, Land, Chemical 5,053,190 1,109,107 50* Reduction FIGURE 16. REDUCTION OF ELITE TYPE. FROM Manual of Statistics, WAR DEPARTMENT, SOS. REPRODUCTION PROCESSES 159 duced for printing to fit a space 4-by-7 inches in size. The reduction in the width dimension, from 8 to 4, is 50 percent, but 50 percent of 15/2 is 7%, which exceeds the height of the printing space. The reduction must, therefore, be calculated from the longer dimension, that is, from 15M to 7, which amounts to approximately 55 percent. Applying this ratio to both dimensions of the chart gives the size of the printing image, 3.6 by 7 inches. A slide rule is a great convenience for solving quickly and accurately problems of this kind. 'If the two chart dimensions are set opposite each other on the rule, the conversion to fit a smaller or larger space can be determined without computation. Figure 16 shows reductions of elite type ranging from 10 to 50 percent of the original size. XVI CLASSIFICATION OF CHARTS BY USE IP CJftE iHE details of the designing, planning, and drafting of a chart are necessarily subordinated to the pur- pose for which it is to be used. The size of the audience, the physical conditions of the locale where the chart is to be shown, and the method of presentation are all factors which enter into the problem. Classified by use, the majority of statistical charts fall within one of the following seven categories: 1. For publication in newspapers, weekly and monthly magazines, or printed reports 2. For general inter-office distribution 3. A single copy for desk use 4. For use in conferences, board meetings, and hearings 5. For permanent or temporary exhibits 6. As graphic illustrations to accompany public addresses 7. For the daily, weekly, or monthly recording of current operations 160 CLASSIFICATION OF CHARTS BY USE 161 CHARTS FOR PUBLICATION 9 Statistical charts appear frequently in the reports, bulletins, and other published material issued by governmental departments and agencies and in trade journals and other periodicals which specialize in studies and articles relating to commercial, industrial, or general eco- nomic subjects. They are rarely used by the widely circulated popular weeklies and monthlies. Occasionally special articles in Sunday news- paper editions are illustrated with charts. Some newspapers run line or column charts picturing the movements of stock and bond prices. With these exceptions statistical charts find little favor in the daily press. The average newspaper reader will skip chart illustrations unless they are strikingly pictorial or relate to a subject in which he is especially interested. The chart has to compete with a variety of other pictorial forms which present information, in such a way that it can be readily assimilated without mental effort. A statistical chart, no matter how clear and simple in design, does demand a little close attention if its message is to be understood. Bar and column designs are generally preferred to the curve types. Sector charts, if they do not contain very small sectors and are not overloaded with lettering, are favored for their pictorial quality. Sim- plicity in design and lettering is, of course, essential. Charts for weekly and monthly magazines require more care in preparation than for reproduction in newsprint. Defects that would not be noticeable in a newspaper stand out clearly on the smooth-finish paper on which magazines are printed. The slight irregularities that nearly always occur in typed lettering show up prominently. The grid ruling and curves, if curve designs are employed, should be lighter than on charts for publication in newspapers. The lettering should be done with a lettering guide or typed. Free- hand lettering on small charts takes too much time and is usually less satisfactory than typewriting. Typed lettering must be clean and neat and free from marks of erasures. If the lettering is stripped on the chart, the work can be speeded by having the lettering and drafting done separately at the same time. The drafting and lettering on charts for printed reproduction can be done piecemeal. The title, scales, and labels may be lettered on sepa- rate pieces of paper and stripped on the chart with rubber cement. In this way if a mistake occurs it can be stripped over with corrected 162 GRAPHIC PRESENTATION SIMPLIFIED copy. Any part of the lettering can be changed as often as may be required. The finished chart sometimes looks like patchwork, but if the stripping is done carefully, no sign of it will appear in the printed copy. The edges of the patches sometimes show a faint dark line, but this is easily cleared up by painting with white ink. Chart 109, in which the title, subtitle, and curve labels were stripped on after the draw- ing was finished, was plated without painting out the edges of the stripping. WAGE-EARNERS AND PRODUCTION, MANUFACTURING INDUSTRIES INDEXES I 1899 TO 1939 400 350 300 250 200 150 100 400 350 300 250 200 150 100 1899 1909 1919 1929 1939 CHART 109. EXAMPLE OF STRIPPED TITLE AND CURVE LABELS. One solution of the lettering problem, illustrated in Chart 110, is the substitution of type lettering set by the printer. If this method is adopted, the title and labels need not appear on the drawing. An additional rough sketch is made for the printer to indicate the location and wording of the title and labels to be pasted on the chart before the printing plate is made. Charts lettered in this way generally present a better appearance than if lettered with guides, and have the advan- tage that less time and work in the drafting process is required. The use of colors, with the exception of red, which comes out black, is inadvisable unless provision is made for color printing. Blues and greens come out fainter than red. Reproduction of light tints is usually CLASSIFICATION OF CHARTS BY USE 163 25 D. C. BUILDING BOOM Numerous small projects tote up to a dol- lar value matching 1941. D. C Building Permits [ExeladM Nearby Coustlw) '53 '54 *5S '5* '57 'S '5t '40 '41 '48 '45 '44 '43 '4 '47 *i. Date W<nhtn*0e Bal Ejrtcrt. Board Or too w^ton *Mt CHART 110. too weak for good printing. If the chart is to be printed in color, the original, drawn and lettered in black, is accompanied by a rough sketch in color to indicate to the printer what portions of the chart are in color and what colors to use. CHARTS FOR INTER-OFFICE DISTRIBUTION Statistical charts are frequently utilized in large offices for circulating information of general interest among heads of departments and super- visory or administrative personnel. If the number of copies required does not exceed fifty, they are generally reproduced by the photostat process. The methods used in preparing the charts are the same as for printed reproduction. Charts for this purpose are often more technical in design and nomenclature than would be practicable or advisable for general publication. If charts for this purpose form part of a typewritten memorandum for photostat reproduction, their width should not exceed that of the accompanying text. Otherwise, the reduction necessary to bring the chart to the required width will also reduce the width of the text. 164 GRAPHIC PRESENTATION SIMPLIFIED CHARTS FOR DESK USE On small charts for desk use, where only a single copy is required, stripping cannot be employed. All the lettering must be done on the sheet containing the drawing. If possible, the title should be in larger lettering than the stub and labels, and done either with a lettering QMC MILITARY PERSONNEL THOUSAND 401 NON -OPERATING PERSONNEL Officer replmctment pool* ofc-v DEC QMC non-operating personnel has Increased since March - second quar- ter average strength was one-third larger than first quarter (17,089 and 22,996, respectively). Unasslgned trainees Increased from 67 to 85 per- cent of total In "pipeline* between 1 January and30 June, while personnel In T/0 unit training declined from 21 to 10 percent of the total Officers In pools declined from 1,582 to 800 in sane period - from 9 to 3 percent of total* Percent In schools re- mained practically the same. Practically no change in June in the percent*of operating personnel physically qualified for overseas service. Percent of physically quali- fied officer operating personnel with- out overseas service declined from 87 to 85 percent of total qualified in June. Corresponding percentage for enlisted personnel Increased from 60 to 64 percent of total in June. MALE OPERATING PERSONNEL PERCENT QUALIFIED FOR OVERSEAS SERVICE Officers Enlisted PERCENT OF PHYSICALLY QUALIFIED PERSONNEL WITHOUT OVERSEAS SERVICE 30 June 1945 PERCENT Officers Enlisted Men PERCENT 35 and / over/ CHART 111. FROM STATISTICAL REPORTS TO THE QUARTERMASTER GENERAL. CLASSIFICATION OF CHARTS. BY USE 165 guide or typed. Free use of color will aid in setting off contrasting elements and contribute to the interest and attractiveness of the chart. The lettering on Chart 111, including the title, was all done on the Vari-Typer. The variety of styles and sizes of interchangeable type provided by this machine is especially advantageous for letter- ing small charts. This example was selected from a series of daily re- ports to the Quartermaster General. The accompanying text comment and summarization of the data was featured in all the reports. The objective was to place at the disposition of the Quartermaster General as quickly as possible the statistical background relating to questions of administration and policy requiring his attention and ac- tion. Through contacts with the chief executive officers the statistical department was kept in close touch with current developments. The selection of subjects for the charts was made on the basis of their immediate interest and importance. The drafting was done on sheets of standard size, punched for filing in loose-leaf binders. Colored shadings were used extensively, but were selected from the patterns most suitable for photostat reproduction, in case a number of copies were needed. Text summaries are a valuable addition to any chart, but, because of the prohibitive amount of space they would occupy in the large letter- ing used on display charts, their use is generally limited to charts of small size. Charts of this type fill a real need. Chart and exhibit rooms serve very well to show to visitors, but it can hardly be expected that a busy executive will depend on them to any great extent for the class of cur- rent information he needs to have immediately available in a form that facilitates quick reference and of a size convenient for desk use. CHARTS FOR CONFERENCES, BOARD MEETINGS, AND HEARINGS The selection of design and size of display charts for conferences, meetings of boards or committees, and other small gatherings is deter- mined mainly by the number of oeople likely to be present. For an ordinary departmental conference of executive heads, display charts around 20-by-30 inches in size will be large enough. If the number taking part in the conference exceeds fifteen or twenty, both lettering and drawing should be larger. If the conference includes representatives of interests widely diverse in character, careful editing of the titles and labels is necessary to make 166 GRAPHIC PRESENTATION SIMPLIFIED them clearly descriptive in terms familiar to everyone. Labels should be placed close to the components and categories. Attempts to show dif- ferent aspects of the data in a single chart are usually ineffective. Unless the chart automatically tells its story it will have to be explained, and charts that require verbal explanation are generally failures. Redundant lettering, unessential ruling, and ornamental borders and curlicues serve only to divert attention from the main purpose of the chart. The lettering should be done, if possible, with lettering guides. Hand- lettering of display size generally lacks finish and uniform spacing. Irregularities in lettering are the first details to catch the eye, and the impression of carelessness or poor workmanship they create detracts seriously from the effectiveness of the chart. The time between the calling of a conference and the date it is to be held is sometimes too short for making up the required number of charts in display size. A method that may be employed in such emer- gencies consists in drafting the charts on small sheets, with stripped typed lettering, for duplication by photostat. Enough copies of the originals are run off to provide each person attending the meeting with a full set of the charts planned for presentation. To obtain the best results with charts for use in conferences or hearings it is essential that the method of presentation be carefully planned and adapted to the order of business likely to be followed dur- ing the meeting. It frequently happens in business conferences that no formal agenda is prepared and the order in which the various subjects will come up for discussion cannot be determined in advance. The best plan in such cases is to distribute the charts separately about the room, so they are immediately available when .they are reached in the course of the discussions. If the agenda is limited to one general subject, the procedure may be similar to that followed in lectures. A speaker, sometimes the chair- man of the conference or a member of the statistical staff that designed the charts, takes charge of the presentation. The charts, placed on an easel or a table, are shown and discussed one at a time. Various details that must be taken into account have to do with the physical conditions of the room in which the meeting is held. They usually offer little difficulty if it takes place in an office or board room equipped with facilities for the placement and handling of the charts. But if it is scheduled for a locale where such essentials as adequate lighting and the necessary furniture and equipment for displaying the charts are lacking, these must be provided before the meeting begins. CLASSIFICATION OF CHARTS BY USE 167 Any last-minute improvisations are very likely to prove unsatisfactory. Nothing so tries the patience of an audience as confusion or delays in the order and method of the presentation. The position and height of the chart stand and adequate lighting are of special importance. Some inconspicuous procedure for disposing of the charts after they are shown is needed. Charts not exceeding 20-by-30 inches in size usually can be laid face down on the table in front of those not yet shown. Charts of larger sizes should be turned over to an assistant for disposal. The speaker should stand at the right, not in front, of the charts, so he will not obstruct the vision of people seated at the side of the room. He can use a pointer two or three feet long to call atten- tion to features of the chart of special significance, without at any time impeding a full view of the chart from all parts of the room. A brief reference to the experience of the War Department Statistics Branch in the course of the series of meetings with the Senate and House Military Committees during the last war, referred to in Chap- ter I, may serve to illustrate the type of problems met with in the use of charts in conferences. Many of the meetings were held in the offices of the War Department, where all necessary equipment and facilities were available. Often, however, for the greater convenience of the Committee members, they took place in committee rooms in the Capi- tol or in the Senate and House Offices, where a number of the re- quirements for successful chart presentation were lacking. Also, as the rooms were in frequent use for other purposes, the time for remedy- ing such deficiencies was limited. In the meetings with the Senate Committee where the attendance seldom exceeded ten, little difficulty was encountered in securing a table or desk large enough and high enough to display the charts full- length to all present. The provision of supplemental lighting was usu- ally unnecessary. As none of the members of the Committee were more than twenty feet from the charts, the labels and titles were clearly legible and reference to them could be omitted in the speaker's verbal introduction to each chart. The attendance in the meetings with the House Committee gener- ally ranged from thirty to forty. This meant that if the charts were placed on an ordinary desk or table only the upper part of them would be visible to those seated beyond the fourth or fifth row of chairs. The stand for the charts had to be built up by one means or another sometimes by piling books on the table or adding a pair of filing-case units to secure sufficient height. Usually the illumination from the 168 GRAPHIC PRESENTATION SIMPLIFIED overhead lighting was inadequate. This was remedied by placing a footlight below the charts. As the labels of curves and segments could not be easily read from the rear of the room, the speaker included in his introductory remarks a complete description of the graphic features of each chart. Questions from the audience were another serious problem. The speaker had to be fairly well informed concerning the subject of each chart and have at hand in convenient form such additional data as might possibly be requested by members of the Committees. A fre- quent request, if the charts represented percentages or index numbers, was for their translation into their basic equivalents, or in the case of curve charts, the high, low, and end points of the curves. Such ques- tions were taken care of by lettering the figures in light pencil above or below these points or on the margins of the charts, where, although not visible to the audience, they were instantly available in answering questions of this kind. Requests for more extensive data were referred to an assistant provided with tables and other source material per- taining to the charts. A few experiments were made with pictorial additions to the charts sometimes characterized the "kindergarten" method consisting in drawings of the objects represented by the curves, bars, and other con- ventional graphic types. For example, if the chart pictured the pro- duction rate of airplane bombs, a drawing of a bomb accompanied the lettering in the stub in bar charts or above the curve in curve charts. It was finally decided that the limited value of such aids to visualization did not justify the time and labor expended on them. CHART EXHIBITS In large offices a room is sometimes set aside to be used exclusively for a permanent chart exhibit. In other cases the exhibit is located in a room used for conferences and board meetings. The commonest defect in chart exhibits is lack of flexibility. The exhibit rooms are filled up with subjects which appear to be of out- standing interest at the moment. Within a short time many of the charts will be out of date unless provision is made for keeping the exhibit in line with the new statistical data received from day to day. As many as possible of the charts should be designed with space left for adding new data. If the time scale in curve and column charts is in months, blank space for at least three additional months should be CLASSIFICATION OF CHARTS BY USE 169 left at the right of the drawing. Otherwise, the drafting room will be confronted each month with the task of making over most of the live charts in the exhibit. The major problem in the maintenance of a chart exhibit is how to keep it alive. Every facility for making frequent changes should be provided. The method employed for fastening the charts in place on the walls or display fixtures should permit their easy removal without tearing or defacing the paper or cardboard. Stapling devices are not adapted for use on charts that must be returned to the drafting room periodically to be brought up to date, or that are likely to be needefl in conferences or for exhibit in another room or building. Within a short time the margins on which the stapling is done become defaced to such a degree that the chart has to be made over. Map tacks, which leave little trace on the chart margins, are commonly used for this purpose. The type of fixture which is shown in Figure 17 is very convenient for exhibits of small- or medium-sized charts. It occupies little space and is portable. The use of wall space is preferable for charts of display size. Multiplex Display Fixture Company FIGURE 17. PORTABLE FIXTURE FOR EXHIBIT OF SMALL CHARTS. Conferences requiring the use of charts are frequently held in rooms where hanging the charts on hooks or tacks is impracticable because of possible injury to the wood paneling or the wall finish. In such cases 170 GRAPHIC PRESENTATION SIMPLIFIED light easels are the best solution, although they have the disadvantage that only one chart at a time can be shown. One of the most important requirements for the display of statistical charts in exhibits is adequate lighting. It must be strong enough to bring out clearly contrasts in color and shading and permit easy reading of the lettering. Overhead central lighting is usually unsatisfactory. Whenever possible, hooded lights should be placed immediately above the charts. Figure 18 shows a wall cross-section of a permanent chart exhibit installed by a Federal agency in Washington. Good lighting is secured with a series of fluorescent lights extending the length of the wall. These are enclosed in a lighting box open at the bottom. The space between the lighting box and the shelf below is large enough for a chart 40 to 42 inches in height. This space is backed with plywood, with an outside layer of heavy cardboard. The slanting shelf below the charts provides space for reports, tables, or other matter relating to the subjects presented in the exhibit. CHARTS FOR PUBLIC ADDRESSES The chief problem in the preparation of charts for use with addresses or discussions before large gatherings is the matter of size. The lettering on a 30-by-40 inch illustration-board chart, unless it is very large, will not be clearly legible at a distance beyond thirty to forty feet. Larger sizes of illustration board are difficult to transport and awkward to handle. If the address is given from the seating level of the room, the utiliza- tion of illustration-board charts is impracticable. Only those of the audience seated near the speaker can obtain a full-length view of the charts. If they are shown from a raised platform, the stand for the charts should be high enough to leave a space of several feet between the lower margins and the floor. The charts should be shown from a central position, one at a time. Distributing them separately at the front of the stage or platform, an arrangement sometimes adopted, saves some handling, but divides the attention of the audience, which should be held to the chart under discussion by the speaker. Strong lighting should be provided if cardboard charts are used, otherwise only those of the audience seated near the speaker will be able to distinguish details in the charts. Footlights, sometimes used for CLASSIFICATION OF CHARTS BY USE 171 f LOOU FIGURE 18. WALL CROSS-SECTION OF A CHART EXHIBIT. 172 GRAPHIC PRESENTATION SIMPLIFIED this purpose, are better than nothing, although the lighting should be from above rather than from below the chart. Lantern-slide projection gives the best results if the audience is too large for the use of illustration-board charts. The charts are first drafted in a size convenient for lettering and then reduced photo- graphically to that of the slides. With a good projector a clear magnifica- tion up to ten feet square or over can be secured. Golde Mfg. Co. FIGURE 19. LANTERN-SLIDE PROJECTOR. While the best results in lantern-slide projection will be obtained only if the room where the charts are shown is in complete darkness, this is often difficult or impossible in large public halls and audi- toriums. The disadvantages of semidarkness can be overcome to a considerable extent if a projector with a high light output is used and the position of the screen with relation to the room lights adjusted so that no light except that from the projector falls directly upon it. The room lights should be controlled, if possible, from the projector position. CLASSIFICATION OF CHARTS BY USE 173 This method solves the problem of size, but involves a few minor complications, among them the position of the speaker. He cannot stand in front of the screen, and at either side will not be seen clearly in the semidarkness required for satisfactory screen projection. This difficulty is usually met by placing in front of the speaker a small table or desk equipped with a hooded desk light. The microphone, commonly employed for the delivery of addresses to large audiences, limits to some extent the speaker's freedom of move- ment. Unless he is accustomed to the use of this instrument, he is likely in the course of his address to turn his head toward the screen to call attention to some especially significant feature of the chart. This will be instantly reflected in a noticeable difference in the tone and volume of his voice. The projector, with the slides arranged in their appropriate order, should be in charge of an assistant who can be trusted not to mix up the chart sequence nor put the slides into the projector upside down. A system of visual signals between the speaker and his assistant should be worked out and practiced until there is no chance of slips in the timing. Charts to be shown with a public address should be extremely simple in design. Colors, shading, and curve patterns designating components and categories should be chosen with an eye to strong contrasts. It is essential that the meaning and purpose of the chart be obvious at a glance. If they are not, the attention of the audience is divided between deciphering the chart and listening to what the speaker has to say about it. CHARTS FOR RECORDING CURRENT OPERATIONS Charts of this type are little more than accounting devices in graphic form. They are used extensively in all classes of industrial and com- mercial activities. They generally consist of a series of dates at the top of the chart and a list of items at the left. The ruling is vertical for the -time scale and horizontal for the items. The entries correspond- ing to each time unit are noted as numbers or symbols or with ad- hesive tape in color or shading. If the chart is laid out on cardboard, map tacks of different colors or shapes may be utilized for the same purpose. Ruled loose-leaf sheets are commonly employed for charts repre- senting a continuous daily record. If the entries are at longer intervals, 174 GRAPHIC PRESENTATION SIMPLIFIED the chart is usually drafted in wall-chart size. A curve or column dis- play chart, if space is left at the right of the drawing for future entries, serves the same purpose. A type sometimes designated "Progress Chart," similar in design, is employed to record progress on a project, study, or investigation with a definite time limit. Usually the time scale is in months, the last month in the series representing the date set for completion. The entries are in percents, showing the proportion of the project finished to the end of each time unit. XVI STATISTICAL PROCEDURES IP ulii I HE foregoing chapters have dealt chiefly with the various stages of design, drafting, and production. This chapter will take up in some detail the procedures employed in the preparation of the statistical material before the chart reaches the drafting stage. In large enterprises or organizations this is a matter with which the draftsman need not concern himself. The initial idea of the chart gen- erally originates with someone exercising managerial or administrative functions. It then passes to the statistical staff, which carries out the necessary research and the collection and analysis of the data. It usually reaches the draftsman in the form of a table suitably arranged for drafting and generally accompanied by a rough freehand sketch out- lining the design selected. There are many small enterprises, however, where the draftsman may be called upon to take over partly or entirely the work of collection and analysis of the data and the preparation of the tables for the charts, as well as their reproduction in typed or printed form. In this case he 175 176 GRAPHIC PRESENTATION SIMPLIFIED will need some knowledge of statistical procedures. A large number of persons are engaged in such work, but only a small proportion call themselves statisticians, and fewer still have had special training in statistics. The fact is that the methods employed in the preparation of data for the majority of charts are simple and easily learned. Some of the most important of these are outlined in the following pages. A brief study of a good text on statistics will give the student all the additional refinements in statistical technique he will ever be called upon to use. Elementary Statistics, by Dr. F. H. Harper, may be especially recom- mended for simplicity and clarity of treatment in terms understandable to anyone with a high-school education. The knowledge of mathematics needed for this phase of the work varies with the nature of the problem. Only rarely will more than a thorough grounding in arithmetic be required. This is true even of the higher flights of statistical analysis, once they are divested of technical terms and mathematical symbols. After the various steps are broken down into everyday English, it will be found that they demand only a working knowledge of eighth-grade arithmetic. ROUNDING Much time will be saved in preparing statistical data for charts or tables by rounding large numbers to three or at the most four digits. Plotting to the fourth digit in any but very large display charts is im- practicable. In tables small numbers save space and are easier to read and understand than large ones. Rounding focuses attention on the more significant digits and reduces the work of calculating the conver- sion of basic figures to relative numbers. In rounding, a digit less than five is dropped. A digit greater than five adds one to the next digit to the left. If the digit to be discarded is an even five, the next digit, if an even number, is unchanged, but if odd, it is raised. Care must be used in rounding series of numbers varying widely in magnitude to avoid undue distortion of the smaller items. For example, the series 150,700, 72,300, and 5,500, if rounded to thousands, becomes 151, 72, and 6. The change in the first two numbers through rounding amounts to less than one half of 1 percent, but the third number is in- creased by over 9 percent. It is best in such cases to add one decimal place in all the rounded numbers. Frequently a column of rounded numbers will not add to the STATISTICAL PROCEDURES 177 rounded total. The difference is usually slight, but a footnote should be added explaining that, because of rounding, the total does not agree with the sum of the items. If the figures are percents, it is customary to increase or decrease by one the right-hand digit of one or more of the larger percents to bring the total to 100. AVERAGES Averages are employed to summarize statistical data. They are com- puted in various ways. The terms designating the two methods most frequently used are "simple," or "unweighted," and "weighted" aver- ages. The simple average is merely the quotient obtained by dividing the total of a series of values by the number of components. Table IV illustrates the procedure. TABLE IV SIMPLE AVERAGE Components Values A 220 B 135 C 365 Total 720 Average 240 If the series contains one or more extreme values, the average may differ so far from any of the individual values or any grouping of them as to be of no real significance. Table V is an example. TABLE V AVERAGE OF A WIDE RANGE OF VALUES Components Values A 75 B 306 C 34 D 26 E 550 F 65 G 29 Total T 1,085 Average 155 178 GRAPHIC PRESENTATION SIMPLIFIED The figure obtained by dividing the sum of the values by the number of components is nearly three-and-one-half times the average of the five smaller values and is 64 percent below the average of the two larger ones. In cases of such wide differences in the range of values, the median, the middle item when the values are arranged according to size, is sometimes used. This arrangement, using the same data, is shown in Table VI. TABLE VI ARRANGEMENT OF VALUES TO DETERMINE THE MEDIAN 550 306 75 65 Median 34 29 26 The median, 65, is more representative of the five lower values than the average, but neither is of much use as a summarization of the whole series. The median is seldom employed in commercial and industrial tables, chiefly because few people are familiar with the term. The same objection applies in lesser degree to "mean" and "arithmetic mean," which are sometimes used for "average." WEIGHTED AVERAGE If both components and values vary in size, the weighted average should be used. Table VII shows the weighted-average cost per unit of a product manufactured in three separate establishments. TABLE VII WEIGHTED AVERAGE Number of Establishment Units Produced Total Cost A 400 $ 4,800 B 1,100 11,900 C . 700 8,600 Total 2,200 $25,300 Weighted-average cost per unit $11.50 STATISTICAL PROCEDURES 179 Weighted averages derived from series in which there are extreme differences in the size of components or values are likely, as in simple averages, to be of little significance for practical use. Averages and percents should not be averaged. The procedure for obtaining a true average of a number of averages or percents is the same as that for the weighted average. The basic values and com- ponent figures from which the individual averages or percents are derived are totaled. The true average is the quotient of the value total divided by the component total. A type of error common in both simple and weighted averages is the inclusion of components which have no bearing on or merely distort the summarization. Errors of this kind are frequent in per capita estimates covering the total population. A recently published rate of per capita consumption of liquor in the United States was calculated by dividing the total consumption by the total population, without taking into ac- count that the population group fourteen years of age and under, num- bering nearly thirty-three million, consumes no liquor. FREQUENCY DISTRIBUTIONS Frequency distributions are distributions of amounts by categories. Table VIII, representing a theoretical distribution of the wage-earners in an industrial establishment by rates of pay per hour, is an example of a simple frequency distribution. TABLE VIII SIMPLE FREQUENCY DISTRIBUTION Rates of Pay Number of Wage-earners Re- gents Per Hour) ceiving Specified Rates 70 12 75 21 80 63 85 75 90 84 95 80 100 74 105 60 110 51 115 36 120 and over 22 180 GRAPHIC PRESENTATION SIMPLIFIED Table IX shows a distribution of wage-earners by weekly earnings, estimated from the data in Table VIII. The number of different individ- ual amounts in an average weekly payroll is too large to show each sepa- rately in a chart or statistical table of reasonable size. For this reason, the data are grouped in class intervals. TABLE IX CLASS-INTERVAL DISTRIBUTION Class Interval Number of ( Dollars Per Week ) Wage-earners 25-29 31 30-34 140 35-39 235 40-44 114 45 and over 58 The class intervals in this table are in groups of five, each interval comprising the items from the first to the last number, including those exceeding the last, but less than the first number of the following class interval. For example, a wage-earner whose pay check amounted to over $44, but less than $45, was classed in the 40-44 interval. The class intervals should be approximately equal in size. Frequently a series is made up chiefly of items which fall within the range of rela- tively small class intervals but ends with several of much greater spread. In Table X the range in each of the first four class intervals is 100, while in the fifth it is 500, and in the sixth, 1,000. Presented in a table, a dis- tribution of this kind may be understood, but it is difficult to make a chart of it that will show a clear picture of the relation between the amounts in the small and large class intervals. TABLE X DIFFERENCES IN RANGE OF CLASS INTERVALS Class Interval Amount 101-200 125 201-300 224 301-400 654 401-500 185 501-1,000 110 1,001-2,000 56 STATISTICAL PROCEDURES 181 INDEX NUMBERS Index numbers are frequently used in the analysis and presentation of statistical data. Published index-number series compiled by govern- mental statistical agencies alone cover an extensive range of economic and industrial activities. Many tables published in economic periodicals include only index numbers, omitting the basic data from which the indexes are derived. The term index number has a technical sound, but it is only another name for percent. A certain figure or figures in a series is selected as the base, with an assumed value of 100. All the figures in the series are then converted to percents of this base. For example, the series 160, 80, 120, 200, if the base selected is the first number, becomes as index num- bers 100, 50, 75, 125. Each of the numbers is divided by the base. The designation "index number" is frequently omitted in tables and charts. The base figure, followed by 100-for example, '1929 = 100," "1941-45 = 100" is lettered in the body of the chart or over the upper ruling of the grid. In typewritten tables it is either typed below the title or over the first ruling of the table. In printed tables it is often set in heavier type. The examples which follow illustrate some of the advantages of this method for use in statistical analysis and particularly its value for comparisons of two or more series of unlike basic units or of extreme difference in size. As the examples are interrelated, the same time series, 1929 to 1937, is used in all of them. This period covers the great depression of 1929-33 and the succeeding recovery move- ment during which various important indicators reached or exceeded the 1929 levels. The data represent important factors in the manufac- turing industry; the charts present the same data in graphic form. The first example shows the use of index numbers for comparing two series which, because of the difference in the nature of the basic units, are not comparable in their original form. The series represent two fac- tors of primary importance, the total number of workers employed and the total amount of time worked. The data in Table XI are estimates of average employment and average hours worked per week in the manu- facturing industries. The estimates were published by the Bureau of Labor Statistics of the U.S. Department of Labor. The employment data include both wage and salary employees, but the changes over the period may be taken as representative of the employment of wage- 182 GRAPHIC PRESENTATION SIMPLIFIED earners, as the salaried employees constitute only an insignificant pro- portion of the over-all totals. TABLE XI EMPLOYMENT AND HOURS WORKED PER WEEK, MANUFACTURING INDUSTRY: 1929 TO 1937 1929 1930 1931 1932 1933 1934 1935 1936 1937 10,534 9,401 8,021 6,797 7,258 8,346 8,907 9,653 10,606 44.2 42.1 40.5 38.3 38.1 34.6 36.6 39.2 38.6 Year Employment ( Thousands ) Hours worked per week The two series are drafted separately in Chart 112. Double-scale charts are sometimes used for comparisons of this kind. Whether com- bined in a single chart with two scales or charted separately, however, the curves, because of the difference in the scales, do not afford a true comparison of the relative changes over the period and offer but little advantage over the tabular presentation. THOUSANDS 12 EMPLOYMENT AND AVERAGE WEEKLY HOURS, WAGE-EARNERS IN MANUFACTURING: 1929 TO 1937 HOURS 50 Employment Average Weekly Hours 1929 '30 '31 '32 35 '36 '37 1929 '30 '31 '32 '33 '34 CHART 112. Both series, converted to index numbers based on 1929 as 100, with a third index, total hours worked, derived from the first two, are shown in Table XII and Chart 113. STATISTICAL PROCEDURES 183 TABLE XII EMPLOYMENT, HOURS WORKED PER WEEK, AND TOTAL HOURS WORKED: 1929 TO 1937 INDEX NUMBERS, 1929 = 100. Year Employment Hours worked per week Total hours worked ( Hours worked per week multiplied by employment ) 1929 100 100 1930 89 95 1931 76 92 1932 64 87 1933 69 86 1934 79 79 100 84 70 56 59 62 1935 84 83 70 1936 92 89 82 1937 101 87 88 AVERAGE EMPLOYMENT AND HOURS WORKED 1929 '30 '31 '32 '33 '34 '35 '36 '37 184 GRAPHIC PRESENTATION SIMPLIFIED Either of two methods may be employed to obtain the third series, total hours worked: (1) Multiply average hours worked by number employed and convert the products to index numbers; or (2) multiply the index of hours by the index of employment and divide the products by 100. The latter method is simpler and shorter, and the index num- bers, after rounding, will be the same. Index numbers from 100 to 1,000 are rounded to three digits, and if less than 100, to two digits. Slightly closer accuracy can be secured by adding one decimal place, but this is offset by loss in simplicity and clarity of presentation. There is no point in straining for microscopic accuracy in relative series which, in reality, can be only approximately exact, particularly if the data repre- sent estimates or averages combined from many sources. Conversion of the basic data to index numbers makes it possible to present them graphically in a form that facilitates exact comparison and interpretation. The volume of industrial production is one of the primary indicators of changes in economic conditions. The first line in Table XIII repre- sents the index for all manufacturing for the years 1929 to 1937 based on the average for the period 1935-39. These data were compiled by the Federal Reserve Board. The second line is the same index converted to a series based on 1929. The conversion is effected by dividing each of the numbers in the Federal Reserve Board index by its 1929 index number, 110. TABLE XIII PRODUCTION, WHOLESALE PRICES, AND VALUE OF PRODUCTION: 1929 TO 1937 Year 1929 1930 1931 1932 1933 1934 1935 1936 1937 Industrial production 110 90 75 57 68 74 87 104 113 (1935-39 = 100) Industrial production 100 82 68 52 62 67 79 94 103 (1929 = 100) Wholesale prices 100 93 82 74 75 83 87 87 92 ( Manufacturing ) Value of production 100 76 55 39 46 61 69 91 95 ( Price index multi- plied by production index ) The first two lines illustrate the procedure for converting series of index numbers from one base to another. The wholesale-price index is compiled by the U.S. Department of Labor. The fourth line, value of STATISTICAL PROCEDURES 185 production, is calculated by the short-cut method described in the pre- ceding example. The three series, production, price, and value, are com- pared graphically in Chart 114. Special care should be exercised to obviate misinterpretation or mis- use of derived indexes through the employment of designations that imply a relationship which may be, in fact, non-existent. The indexes "Output Per Worker" and "Per Hour," derived by dividing the index of production by the indexes of employment or man-hours, are examples. Changes in these indexes are sometimes assumed to indicate that cor- responding changes have taken place in the productiveness or efficiency PRODUCTION, WHOLESALE PRICE AND VALUE OF PRODUCTION 186 GRAPHIC PRESENTATION SIMPLIFIED of labor, although this interpretation has no basis in fact. The course of these indexes through the period 1929 to 1937 illustrates this point. Both the basic and the derived indexes are shown in Table XIV. TABLE XIV OUTPUT PER MAN AND PER HOUR, MANUFACTURING: 1929 TO 1937 Year 1929 1980 1931 1932 1933 1934 1935 1936 1937 Basic Indexes Employment 100 89 76 64 69 79 84 92 101 Total hours worked 100 84 70 56 59 62 70 82 88 Output (Production index) 100 82 68 52 62 67 79 94 103 Derived Indexes Output per man ( Output index 100 92 89 81 90 85 94 102 102 divided by employment index ) Output per hour ( Output index 100 98 97 93 105 108 113 115 117 divided by totat-hours index ) The basic indexes, employment and total hours worked, differ funda- mentally in that the hourly unit is constant while the employment unit ranges from part-time work during the depression years to full-time in the recovery. An employee working three days a week is not, for the purpose of the comparison shown by the derived indexes, the same "man" as one working five or six days a week. The curves in Chart 115 are not indicative of either decline or in- crease in the average contribution of labor. It is highly unlikely that efficiency per man or per hour decreased during the depression. In fact, if the general tendency in the reduction in working forces that took place, to retain as far as possible the highly skilled workers, is taken into account, it is probable that the average productive capacity of labor rose rather than fell during that period. The curves reflect in the earlier years the general slowing-down of the whole productive process, due to lack of demand and disorganized markets. In the rise that fol- lowed, improved equipment and economies in production methods developed from the experience gained during the depression contrib- uted heavily to the gain in rate of production. These factors alone accounted to a considerable extent for the increase in ratios of output per man and per hour. The foregoing examples, covering a few significant factors in a typi- cal economic problem, illustrate some applications of the index method in statistical research and analysis. The numerous economic indexes published by public and private statistical agencies can often be em- ployed in background studies for comparison with developments on a STATISTICAL PROCEDURES 187 OUTPUT PER MAN AND PER HOUR 80 60 1929 '31 '32 '33 '34 CHART 115. 35 '36 '37 smaller scale in individual enterprises. As the indexes are immediately available, studies of this general nature can be made with a minimum expenditure of time and effort. All the basic indexes used in the index- number examples were taken from a single volume, the Statistical Abstract of the United States, published by the U.S. Department of Commerce. The tables were done in one day by one person, including computation of the derived indexes. If the calculations are made without the aid of computing machines, the closest possible rounding consistent with a fair degree of accuracy should be employed to shorten and simplify the work. Even with ma- 188 GRAPHIC PRESENTATION SIMPLIFIED chines the use of large figures is usually unnecessary. Investment in a good slide rule will pay handsome dividends in economy of time and tedious computation. Anyone can learn to use a slide rule with an hour or so of practice. For computing percentages or other ratios which do not run beyond three digits, it is faster than a machine. All of the derived series in the index-number tables were computed with a twenty- inch slide rule. A smaller size may be used for determining the pro- portions of charts and for multiplication or division to two digits, but for close work to three digits a longer rule is required. Rough sketching is an invaluable aid in statistical analysis. Relation- ships whose significance would become apparent only after careful study of the same data in a table stand out instantly in a sketch. For this purpose pencil sketches on printed graph paper will serve quite as well as inked charts plotted exactly to scale. XVI PLANNING, TABULATION, AND PRESENTATION OF TABLES HE first requisite in planning a table is a clear understanding of what the table is for and how it is to be used. Once the objectives are determined and the sources outlined, the succeeding steps are: 1. Lay-out of tabulating sheet 2. Tabulation, followed by check to sources 3. Addition of columns and computation of derived figures, if any, followed by check 4. Lay-out of stubs, columns, and column heads for typing 5. Typing, followed by check to tabulating sheet TABULATING SHEETS Careful design of the lay-out for the tabulating sheet will obviate complexity and confusion and save time, labor, and mistakes. It should be arranged so that, as far as possible, numbers to be compared are in 189 190 PLANNING AND PRESENTATION OF TABLES 191 the same column. Comparison of numbers is easier when they appear one above the other rather than side by side. Units should be aligned vertically with units, and decimals with decimals. In tabulations con- taining both basic and derived figures a blank column should be left at the right of each basic column for recording the derived figures. In the final typed table the basic columns should go side by side at the left of the table and the derived columns side by side at the right. The reader compares derived figures with each other, not with the basic figures. The series of numbers and stub entries should be broken down into groups for convenience in tabulation, copying, and reading. In some tables, of which Table XV is an example, the arrangement in groups is determined by the nature of the data. Otherwise the usual practice is to leave a blank line after each five items. Monthly figures can be arranged in quarterly or semiannual groups. Ledger-ruled paper is often used for tabulating purposes, but the columns are usually too wide, with the result that the table occupies more space than is necessary, is awkward to handle, and must be folded two or three times to get it to a size convenient for filing. For general use a specially prepared form about ll-by-17 inches in size, ruled in columns one-half inch wide, with quarter-inch horizontal ruling, pro- vides sufficient space for all but extremely wide tables and when folded once will fit in a standard filing cabinet. UNITS OF VALUE When the unit of -value is the same for all the columns, it is customary to place it under the title ( see Table XV ) . If it applies to some of the columns, but not to all, it may be lettered in a box head, as shown in Table XVI, on page 192; and, if it applies to a single column only, it may be shown at the foot of the column head. TITLES The title should be a concise but fairly complete description of the subject-matter. The facts the table shows should be emphasized by naming them at the beginning of the title. Such forms as "Table Show- ing/' "Number of," and "Distribution of in table titles and column headings should not be used unless they are essential to a clear descrip- tion of the data. In the typed copy, titles should be centered above the table. If they K> VO CMCOlf\CUCO VOCMCOlTN rH i M< ajg CVJ ^ rH^^rHr- ^rHt-^ -1 1 rH OJ S c i t O rH <D O 05 <n < s O ^i ON if\ CM CO iT\ N^OMPvCM ON CM cO-*rHr--ct CMCO-*H -p C g CO <H h- roo VO rT\ , it rc\ O i Vb R ft2<S^rH g^R^C^ PH 1 Tj i -H a> ir\ co -H/or rr\o co-3-ot^- CO ^s ^ - S^ftaS 1 ^*ft i <! -tf > CM ir\ rHr--H/ot^- if\rH r-^t rH -=f CTVO rOv ONVO ^t O VO KN, O K^ OMTvCMCOlfN f^NOMfNCM M K S * CO rH t-- H 8 fe I t"^ ON VO rTN. O VO K> rH t^ rTN O w 1 rH M rH H PH r-l KN IP\ CM ONVO CM O\ t~- rT\ O\VO CM -* >< 1 rH O H -4- rHCOtAHCO VO CMXX3 ITN O K^\ O t^-* Of lT\rH t -* ON CM O\VO K> ONVO -d- O VO rfN . B O 1 03 <C M CO rH CO ifN. 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CM CO r-rrvONiT\ | co " 1 t* O CM CO -^J" rH t^ VO CM CO -^ VO ON rHf K"NOVO u-Xr-lf-'KN IfN CO OVOCMONlfN -d-OVOCM o mC^ r CO -4- f O\lT\rHCO-* rTNONlPvrH r("N VO CO -4" O r rT\ CMCO -H; O CM^ tr\ t-N^ONVO r-lt--rrNON rH -d" g . : i? w P3 4 t I J a C c t ) 1 4 PJ ; ? r i 3 (-1 > o i l i 2 . . -rH BJ rH <a 3 I -5 s *s|^ . . -( CD -0 W a) <Df^ -Hgq < SZ Bt-i OO 'tt)G-H OS rH " PL, 4J a) H OT < EH CO EnO CO H 192 PLANNING AND PRESENTATION OF TABLES 193 run into more than one line the second line also should be centered and, if possible, be shorter than the first. Abbreviations should not be used in titles and subtitles. STUBS The items in the stub should be edited to as uniform a maximum length as is possible without employment of unfamiliar abbreviations. Long stub items should be written in two or more lines. In tables where the list of items is broken down into groups the usual practice is to letter the title of the group at the left of the stub column and indent the subordinate items two or three spaces. This arrangement is shown in Table XV. If the subordinate items are longer than the group title, the arrangement may be reversed, as in Table XVI. The order of items in the stub should follow a logical sequence. This may be quantitative, progressive, chronological, or alphabetical. Ascending or descending order of rank in the attribute in which the items are compared facilitates easy reading and interpretation. Any miscellaneous or combined group, such as "All other," should appear at the end of the list rather than in order of its size. The total may be the first or the last line of the table. TABULATION The data should be recorded in black pencil. The No. 2 or 2% is best for this purpose. A pen should not be used, as frequent era- sures are unavoidable. An erasing shield will help to prevent smudgy erasing. Much time will be saved in tabulation by working in twos. One per- son reads off the figures from the original source, the other records them on the tabulating sheet. The data for a single table may be drawn from a number of documents, reports, schedules, or other sources, which differ in shape, size, and arrangement. One person working alone on such a tabulation will take three or four times as long as two > working together and will make more mistakes. The same method will save time in "reading back" to sources. Errors are more easily noted when read aloud. Verification by reading back, however, is not an absolute guarantee of accuracy. The work is monotonous, and, if it is continued for some time, the attention may wander because of boredom or fatigue. Where 194 GRAPHIC PRESENTATION SIMPLIFIED tape adding machines are used, the tapes, if properly labeled, can often be used to save time and work in verification. Some tables permit the use of a method that reduces materially the probability of errors. The lines as well as the columns are totaled. If the entries and the additions have been made correctly, the sum of the line totals will exactly coincide with the sum of the column totals. COLUMN WIDTHS In typed tables the width of the columns should be as uniform as the size of the figures and the number of the columns will permit. If crowded for space, the minimum width necessary for individual col- umns can be determined by counting the digits and punctuation marks in the largest figure of each column and adding two blank spaces for ruling. Long column heads" should be typed in several lines to fit the space required by the figures below them. The last three columns in Table XVI are examples. The practice of basing the width of columns on the space needed for long column heads written in one or two lines often results in columns that are far wider than is necessary for the data and a table that is too wide for typing on a machine of stan- dard size. CAPITALIZATION Titles should be capitalized throughout. In typed tables spaced capitals underlined are often used for short titles. Only the initial let- ter of the first word in subtitles is capitalized, with the exception of words normally written with initial capitals. The same rule applies to stub titles and column headings. PUNCTUATION The title should not end with a period. If it consists of two sentences or independent phrases, a period follows the first but is omitted after the second. Periods are not used in column headings or stub items except where required for abbreviations. Commas should be used to separate thousands from hundreds and millions from thousands. Lead- ers, a line of spaced periods between stub titles and the first vertical ruling, are usually included in typed tables. Ditto marks should not be used. PLANNING AND PRESENTATION OF TABLES 195 If the data represent money, the dollar sign should be typed before each number in the first line, and repeated before the total if this is placed at the bottom of the table. It may be omitted if the data are rounded and the rounded unit is indicated below the title or in a column head. SYMBOLS All spaces to the right of each stub item must be filled in. The sym- bols used to indicate that the data for a particular item are lacking vary widely. The zero, the single dash, and the double dash are often used for this purpose and are quite as often misunderstood. The data may be lacking for various reasons. The collection of information concerning a particular item may have been discontinued, or the information may not be pertinent or necessary for the purpose of the table, or the data may not have been received when the tabula- tion was made. A footnote defining or explaining the omission is preferable to arbitrary symbols whose meaning is often not clearly understood. The footnote symbol most commonly used in typed tables is a com- bination of an underlined letter and an oblique, _a/. It occupies only two spaces but requires backspacing for the underline. Another, less frequently employed, is a combination of letter and parentheses, (b). The use of the asterisk and double asterisk is usually limited to tables with not more than two footnotes. RULING Methods in use for ruling statistical tables differ to some extent in minor details, but the following rules are generally applicable. The ruling is done in India ink with a ruling pen. A light double rule or a single heavy rule is drawn from margin to margin above the stub and column heads. The horizontal separations of the box and column heads are in single light rules. Single light vertical rules are drawn between columns. The sides of the table should be left open, without ruling. Totals and grand totals should be separated from other numbers by heavier single rules, vertical if the totals are at the right, horizontal if they are at the bottom of the table. Averages should be set off in the same manner. INDEX Abbreviations for time scales, 13 Ahesive screens, 7, 77 on display charts, 147 on maps, 107 samples of, 6 Airbrush, coloring with, 151 "All-items" bar, 70-71 American Standards Association, 3, 10 Amount scales, distribution of, 12, 13 labeling of, 14 number of units in, 14 100 percent base for, 18, 20-21 position of, 14 repetition of, 86 rulings for, number of, 14, 16, 17 single, 43 zero base for, importance of, 18 omission of, 18 Apprentice training, 8 Area-bar charts, 67 Arithmetic charts, 46, 52 Arithmetic scales, 44, 45 Army Service Forces, Control Division, Statistics Branch, 50 Averages, 177 averaging, 179 moving, 26-27 progressive, 27 simple, 177 in tables, 195 unweighted. See Simple. weighted, 178 of wide range of values, 177 Ay res, Leonard P., 5 Band charts. See Strata charts. Bar-and-symbol charts, 65-67 197 Bar charts, 54-75 advantages of, 54 base figures in, 70-71 broken bars in, 54-55 compared with circle charts, 95 compared with sector charts, 96, 97 components in, order of, 58-59 keys in, 63-64 lay-out of, 133-138 lettering on, 60 lettering versus scales in, 55-58 100 percent base in, 68-69 ruling in, 59-60 stubs in, 71-72 Bar pictorial charts, 113-115 Bars, broken, 54 on map charts, 108 optical distortion in, 67-68 segmented, use of black in, 67 Base figures in relative-number charts, 70 Base lines, weight of, 27 Board meetings, charts for, 165 Borders, 13, 60 Bow pens, 144, 145 Brinton, Willard C., 1, 147 Business-activity charts, 40 Capitalization, in tables, 194 Cardboard, mounting on, 152 Charts, area-bar, 67 arithmetic, 46, 52 band. See Strata charts. bar, 54-75, 95, 96, 97, 133-138 bar-and-symbol, 65-67 bar pictorial, 113-115 business-activity, 40 198 INDEX Charts, contd. cardboard-mounted, 152 circle, 90-95,123-125, 141-142 circular-bar, 125-126 classification of, by use, 160-174 column, 76-89, 122, 133-136, 138-140 components of, 10-11, 13 condensation afforded by, 5 for conferences, board meetings, and hearings, 165-168 cumulative-curve, 28, 29 curve, 10-31, 77-79, 133-136, 140 for desk use, 164-165 deviation-bar, 69-70 deviation column, 88-89 display, 146-152 enlargement of, 155, 157 for exhibits, 168-170 frequency-distribution, 119-120 on graph paper, 127, 128, 130, 131 grouped-bar, 62, 63 grouped-column, 83-84 horizontal-bar. See Bar charts, index log, 52 index-number, 18-21, 47 for inter-office distribution, 163 joined-bar, 61, 136-137 line. See Curve charts, logarithmic. See Rate-of-change charts. on loose-leaf paper, 165, 173 map, 104-111 multiple-scale, 30 multiple-time-scale, 30 organization, 123 paired-bar, 64-65 pictorial, 112-115 pie. See Sector charts, progress, 174 for public addresses, 170, 172-173 for publication, 161-163 ranking, 116-119 rate-of-change, 44-53 ratio. See Rate-of-change charts, for recording current operations, 173- 174 reduction of, 155-159 relative-variation, 120-122 reproduction of, 153-159 rolled, 151-152 sector, 96-103, 141-142 semi-logarithmic. See Rate-of-change charts. Charts, contd. sliding-bar, 74, 75 spaced-bar, 61, 138 staircase-curve, 30-31, 41 statistical map. See Map charts. step-bar, 73 stock-price, 28, 29 strata, 33-34 surface-curve, 32-43 typewritten, 130, 131 on unruled paper, 132-145 versus tables, 5 vertical-bar. See Column charts. Charts: How to Make and Use Them, I Circle charts, 90-95 compared with bar charts, 94, 95 comparison of equal amounts with, 123-125 errors in drafting, 90-91 lay-out of, 141-142 size of, method for calculating, 91-93 Circles, on column charts, 84 on maps, objections to, 108 Circular-bar charts, 125-126 Class intervals, 119, 180 Colors, adhesive, 7 in contrasting net changes, 38 on display charts, 147, 149, 151 on graph-paper charts, 130 on map charts, 105 on multisegmented bars, 75 in organization charts, 123 in printed charts, 162-163 Column charts, 76-89 compared with curve charts, 77-79 with curves, 84-86 labels in, 76-77 lay-out of, 133-136, 138-140 relative-variation, 122 spaced and joined columns in, 80-82 with tables, 82-83 uses of, 76 Columns, hollow, 80 labeling, 76-77 on map charts, 108-110 and spacing, 139 width of, in tables, 194 Compass, 141, 142 Components, chart, designation of, 10- 11, 13 order of, in bar charts, 58-59 Conferences, charts for, 165-168 Crayons, use of, on display charts, 151 INDEX 199 Cumulative-curve charts, 28, 29 Current operations, charts for record- ing, 173-174 Curve charts, 10-31 bases in, 18-21 compared with column charts, 77-79 curve patterns in, 17-18 keys in, 31 lay-out and plotting of, 133-136, 140 omission of time-scale ruling in, 23- 24 plotting points in, 24 proportions of, 13-14 scale numbers in, 14 scale rulings in, 14, 16, 17 time scales in, 13, 22 Curves, broken, 28 on column charts, 84-86 fitted, 22-23 on map charts, 108-110 moving-average, 26-27 patterns of, 17-18 progressive-average, 27 steep, distortions produced by, 34 Cut-out letters, 143 Dash lines, for connecting segments, 77 Desk use, charts for, 164-165 Deviation-bar charts, 69-70 Deviation-column charts, 88-89 Diameters, circle, calculation of, 92 Display charts, 146-152 coloring of, 147, 149, 151 equipment for, 147-148 lay-out of, 147-148 lettering of, 148-149 limitations of, 146-147 mounted on cardboard, 152 rolled, 151 Distortion, in bars, 67-68 in pictorial charts, 112 produced by steep curves, 34-35 Dot maps, 107-108 Drafting, inducements for learning, 7 mathematical requirements for, 176 order of operations in, 145 Drafting courses, 9 Drafting table, 147-148 Drawing board, 132 Drop pens, 144, 145 Easels, for chart exhibits, 170 Elementary Statistics, 176 Enlargements, 155, 157 Equipment, 127, 132 for display charts, 147-148 improvements in, 6-7 Exhibits, chart, 168-170 Explanatory notes, 48, 50 Flow maps, 111 Footnotes, 195 Freehand lettering, 6-7, 143, 148-149, 161, 166 French curve, 132 Frequency-distribution charts, 119-120 Frequency distributions, 179-180 Gelatin duplicators, 155 General Staff conferences, 4 Geometric forms, 91 Graphic Methods for Presenting Busi- ness Statistics, 1 Graphic Methods for Presenting Facts, Graphic Presentation, 1 Graph paper, charts on, 127, 128, 130, 131 samples of, 129 Grids, defined, 13 dimension of, 13-14 lay-out of, 133-134 rate-of-change, ruling of, 44-45 scale for laying out, 49 weight of lines in, 27 Grouped-bar charts, 62, 63 Grouped-column charts, 83-84 Hand-lettering, 6-7, 143, 148-149, 161, 166 Harper, Dr. F. H., 176 Hatching, by hand, 7 Hearings, charts for, 165-168 Horizontal-bar charts. See Bar charts. Illustration board, use of, for display charts, 148 Indexes, basic and derived, 186 Index log chart, 52 Index-number charts, base in, 18-21 versus rate-of-change charts, 47 Index numbers, 181-188 Inking, 144 Inter-office distribution, charts for, 163 200 INDEX Joined-bar charts, 61 lay-out of, 136-137 Keys, for bar charts, 63-64 for curve charts, 31 for grouped-column charts, 83-84 for map charts, 111 Lantern slides, 172-173 Lay-out, circle-chart, 141-142 column-chart, 138-140 curve-chart, 140 display-chart, 147-148 grid, 48, 133-134 joined-bar, 136-137 sector-chart, 141-142 spaced-bar, 138 Leroy Lettering Guide, 149 Lettering, on bars, 55-58, 60-61 basic and derived figures, 86-87 with cut-out letters, 143 on deviation-bar charts, 69-70 on display charts, 146, 148-149 hand, 6-7, 143, 148-149, 161, 166 irregularities in, 166 with lettering guide, 6, 143, 148-149, 161, 166 points of greatest interest, 32, 38, 8.8 printed, 162 for printed reproduction, 161-162 radial, 99 of sector charts, 99 stripped, 161-162, 164 typewritten, 130, 143, 155, 161 versus scales, 55-58 Lettering-guide alphabet, 150 Lettering guides. See Lettering. Lighting, for chart exhibits, 170 for conferences, 166, 167-168 for public addresses, 170, 172 Line charts. See Curve charts. Logarithmic charts. See Rate-of-change charts. Map charts, 104-111 with circles, 108 coloring, 105 with columns, bars, or curves, 108- 109 with dots, 107-108 flow, 111 keys for, 111 limited uses of, 104 Map charts, contd. outlines for, 104 with pins or tacks, 110 with surface designations of cate- gories, 105-107 Map tacks, 110 Median, 178 Microphone, use of, in public addresses, 173 Military Committees, Senate and House, 5, 167-168 Mimeoscope, 155 Moving-average curves, 26-27 Multilith, 155 Multiple-scale charts, 30 Multiple-time-scale charts, 30 Nomenclature, standardization of, 3 Norm, 69 100 percent base, 18-21, 68-69 Operations, order of, 145 Optical distortion, in bar, 67-68 produced by steep curve, 34-35 Order of values, ascending, 59 descending, 59 Organization charts, 123 Outline maps, 104 Paint, use of, on display charts, 150- 151 Paired-bar charts, 64-65 Paper, 143 Parallel rule, 148 Percents, averaging, 179 rounding, 177 Photo-offset, 154 Photostat, 153-154 Pictorial charts, 112-115 symbols for, 113-114 Pie charts. See Sector charts. Pin maps, 110 Plotting, of amounts, bar charts, 137, 138 column charts, 139-140 curve charts, 140 points, 24-25 yearly and monthly, 22 Progress chart, 174 Progressive-average curves, 27 Protractor, 141, 142 Public addresses, charts for, 170, 172- 173 INDEX 201 Publication, charts for, 161-163 Punctuation, in tables, 194 Quartermaster General, 165 Radial lettering, 99 Ranking charts, 116-119 Rate-of-change charts, 44-53 explanatory note necessary in, 48, 50 grid ruling of, 44-46 grids, lay-out of, 48 limitations on use of, 50, 52-53 multicurve, 50 omission of scale rulings in, 46 versus index numbers, 47 Ratio charts. See Rate-of-change charts. Reductions, 155-159 Relative-variation charts, 120-122 column design, 122 curve design, 121 Reproduction processes, 153-159 Rolled charts, 151-152 Root-two dimensions, 13-14, 15 Rough sketching, 188 Rounding, 176-177 Ruling, in bar charts, 58, 59, 60 combined with ticks, 16, 17 in curve charts, 14, 16, 17, 23-24 elimination of, 43 excessive, 14, 16, 17 graph-paper, samples of, 129 rate-of-change scale, 44-46 replaced by ticks, 16, 17 of tables, 195 Ruling pen, 144 Scale rulings. See Ruling. Scales, arithmetic, 44, 45 elimination of, to gain space, 43 for laying out rate-of-change grids, 49 tape, 134-136 triangular decimal, 134 use of, in bar charts, 55-58 See also Amount scales, Time scales. Sector charts, 96-103 compared with bar charts, 96, 97 lay-out of, 141-142 lettering of, 98, 99 miniature, 100-101 overloading of, 102 use of shading in, 101-102 Sectors, grouping of, 99 order of, 96, 99 separation of, for emphasis, 101 totals of, indicating, 102-103 Segment labels, bar charts, 57 column charts, 76-77, 87 Semi-logarithmic charts. See Rate-of- change charts. Shading, adhesive screens for, 6, 7, 77, 107, 147 care in using, 67-68 contrasting net changes with, 38 differentiation of trends with, 32, 33 in grouped-bar charts, 63 in grouped-column charts, 83 in map charts, 105, 107 in sector charts, 99, 101-102, 103 for showing net results, 36 for showing significant time periods, 36-38 in staircase-curve charts, 41 versus solid black, 42 Simple average, 177 Slide rule, for computing diameters, 92 for computing index numbers and percentages, 188 in determining reductions or en- largements, 159 Sliding-bar charts, 74, 75 Spaced-bar charts, 61 lay-out of, 138 Square roots of decimals, 93 Staircase-curve charts, 30-31, 41 Statistical map charts. See Map charts. Statistics Branch, Control Division, Army Service Forces, 50 Statistics Branch, General Staff, 3 Stencils, 155 Step-bar charts, 73 Stock-price charts, 28, 29 Strata charts, 33-34 Stripping, 161-162 Stubs, adjustment of, to save space, 71- 72 defined, 10, 13 lettering, on bars, 60-61 ruling under, 58 in tables, 193 Surface-curve charts, 32-43 for business-activity charts, 40 contrasting net changes in, 38 differentiation of trends in, 32-33 202 INDEX Surface-curve charts, contd. miniature, 38-40 shading versus black in, 42 showing net results in, 36 significant time periods in, 36-38 staircase-curve design of, 41 strata, 33-34 Symbols, in bar-and-symbol charts, 65- 67 footnote, 11, 195 in tables, 195 Tables, 189-195 capitalization in, 194 column widths in, 194 combined with charts, 82-83 preparation of, 189 punctuation in, 194-195 ruling of, 195 stubs in, 193 symbols in, 195 tabulating sheets for, 189, 191 tabulation of, 193-194 titles of, 191, 193 units of value in, 191 versus charts, 5 Tabulation sheets, 189 191 Tabulation, 193-194 Tack maps, 110 Tape scales, 134-136 Text summaries, 165 Ticks, combined with ruling, 16, 17 defined, 10, 13 ruling replaced by, 16, 17 Time scales, abbreviations for labeling, 13 break in, 21-22 distribution of, 12, 13 Time scales, contd. in multiple-time-scale charts, 30 number of rulings for, 14, 16, 17 as plotting points, 24 ruling of, omission in curve charts, 23-24 separation between years in, 14 Time series, 10 Time Series Charts, A Manual of De- sign and Construction, 1 Titles, chart, 13 table, 191, 193 typewritten, 130, 131 "Total" bar, 70-71 Totals, in tables, 195 Training, methods of, 8-9, 127-131 reduction in length of, 7-8 Trends, projection of, 10 Triangles, 132 use of, in lay-out and plotting, 134, 136, 137 Triangular decimal scale, 134 T-square, 132 use of, in lay-out, 134, 136 Typewritten charts, 130, 131 Units of value, tables, 191 Unweighted average. See Simple average. Values, order of, 59 units of, in tables, 191 Vari-Typer, 143, 165 Vertical-bar charts. See column charts. Weighted average, 178-179 Zero base, 18, 46, 120 FUNK & WAGNALLS New Desk Standard Dictionary Featuring EMPHATYPE the surest, simplest way of showing how to pronounce a word literally at a glance this big dictionary brings you everything you need in a desk dictionary for home or office use. 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