The stems are listed to the left of the vertical line. It is important that each stem is listed only once and that no numbers are skipped, even if it means that some stems have no leaves. The leaves are listed in increasing order in a row to the right of each stem. It is important to note that when there is a repeated number in the data (such as two 72s) then the plot must reflect such (so the plot would look like 7 | 2 2 5 6 7 when it has the numbers 72 72 75 76 77). Key: Leaf unit: 1.0 Stem unit: 10.0 Rounding may be needed to create a stem-and-leaf display. Based on the following set of data, the stem plot below would be created: −23.678758, −12.45, −3.4, 4.43, 5.5, 5.678, 16.87, 24.7, 56.8 For negative numbers, a negative is placed in front of the stem unit, which is still the value X / 10. Non-integers are rounded. This allowed the stem and leaf plot to retain its shape, even for more complicated data sets. As in this example below: Key: Usage Stem-and-leaf displays are useful for displaying the relative density and shape of the data, giving the reader a quick overview of the distribution. They retain (most of) the raw numerical data, often with perfect integrity. They are also useful for highlighting outliers and finding the mode. However, stem-and-leaf displays are only useful for moderately sized data sets (around 15–150 data points). With very small data sets a stem-and-leaf displays can be of little use, as a reasonable number of data points are required to establish definitive distribution properties. A dot plot may be better suited for such data. With very large data sets, a stem-and-leaf display will become very cluttered, since each data point must be represented numerically. A box plot or histogram may become more appropriate as the data size increases. Non-numerical use a│abdeghilmnrstwxy b│aeioy c│h d│aeio e│adefhlmnrstwx f|aey g│iou h│aeimo i│dfnost j│ao k│aioy l│aio m│aeimouy n│aeouy o│bdefhikmnoprsuwxy p│aeio q│i r│e s│hiot t│aeio u│ghmnprst v│ w│eo x│iu y│aeou z│aeo Stem-and-leaf displays can also be used to convey non-numerical information. In this example of valid two-letter words in Collins Scrabble Words (the word list used in Scrabble tournaments outside the US) with their initials as stems, it can be easily seen that the top three initials are , and . Notes References