Here is my answer to the axis reversal question, one that has been in my text book since its first edition in 1963 "Readers trained in other disciplines often wonder why economists plot demand curves with price on the vertical axis. The normal conven?tion, which puts the independent variable (the variable that does the explaining) on the horizontal axis and the dependent variable (the variable that is explained) on the vertical axis, calls for price to be plotted on the horizontal axis and quantity on the vertical axis. The axis reversal-now enshrined by a century of usage-arose as follows. The analysis of the competitive market that we use today stems from the French economist Leon Walras (1834-1910), in whose theory quantity was the dependent variable. Graphical analysis in economics, however, was popularized by the English economist Alfred Marshall (1842-1924), in whose theory price was the dependent variable. Economists continue to use Walras's theory and Marshall's graphical representation, and thus draw the diagram with the independent and dependent variables reversed-to the everlasting confusion of readers trained in other disci?plines. In virtually every other graph in economics the axes are labelled conventionally, with the dependent variable on the vertical axis." Lipsey, Richard G. and Alec Chrystal (1995), An Introduction to Positive Economics (eighth edition), (Oxford: Oxford University Press), pp 64 (FN #3). Richard G. Lipsey