  Jevons' use of statistics in the social sciences was inspired by Adolphe Quetelet. Jevons distinguishes between a ‘mean’ (the approximation of a definite existing quantity) and an ‘average’ or ‘fictitious mean’ (an arithmetical average). The fictitious mean is important, since it allows us to ‘conceive in a single result a multitude of details’. For instance, Jevons equates aggregate and average consumption: provided that the community under consideration is large enough, the average consumption of the aggregate community will vary continuously due to price changes, whereas individual behaviour is strongly affected by accidents. If all individuals had exactly the same features (those relevant for consumption), then the average laws of supply and demand would be equal to the conduct of every individual. If however the “powers, wants, habits, and possessions” of different people were widely different, then the average would not represent “the character of any existing thing”. The accidents would cancel each other out and a certain ‘typical’ consumer would emerge. Although this is clearly a case of a fictitious mean, it would not be less useful: “the movements of trade and industry depend upon averages and aggregates, not upon the whim of individuals”.