A Divisia index is a theoretical construct to create index number series for continuous-time data on prices and quantities of goods exchanged. The name comes from François Divisia who first proposed and formally analyzed the indexes in 1926, and discussed them in related 1925 and 1928 works. The Divisia index is designed to incorporate quantity and price changes over time from subcomponents that are measured in different units, such as labor hours and equipment investment and materials purchases, and to summarize them in a time series that summarizes the changes in quantities and/or prices. The resulting index number series is unitless, like other index numbers. In practice, economic data are not measured in continuous time. Thus, when a series is said to be a Divisia index, it usually means the series follows a procedure that makes a close analogue in discrete time periods, usually the Törnqvist index procedure or the Fisher Ideal Index procedures. Uses Divisia-type indices are used in these contexts for example: Multifactor productivity calculations use quantity indexes which incorporate changes in the expenditure share and overall quality of the underlying goods, and are then multiplied by prices. A Divisia index of all measured outputs can be divided by a Divisia index of all measured inputs to get an estimate of the productivity change that occurred apart from the changes in inputs. Aggregation of different monetary pools, e.g. cash and credit card borrowing and different currencies. Here the pools of various monetary aggregates are treated as a quantities, and the prices are usually taken as fixed, but their weights vary -- for example, the Bank of England has an index of the money stock that is available for transactions. The index weights the various money pools by the likelihood they will be used in transactions in the near run -- physical cash and checking accounts are ready to be spent, whereas long term bonds which are not ready to be spent. The interest rate received on the various money pools is a measure of the weight; pounds in cash count more than pounds in bonds. Movement of money from one form to another affects the index whereas it would not affect a simple sum of the money stock; thus the index is more useful to track the money ready-to-transact than a sum would be. Divisia monetary aggregate indexes for the United States, based on William A. Barnett's (1980)