Almost nobody talks about "price parity" any more. A few decades back the term was the common coin of politcal debate, central to arguments about agricultural price subsidies. During the depression, Rooseveltian economists decided that a period about 20 years before that , 1910-1914, had been a golden age for farmers. The price of goods farmers had to buy (made by urban folk) were in a "parity" with the price of the goods they were selling, their crops and slaughtered critters. So (the Brain Trust decided) the goal of federal policy ought to be to get back to that parity. Ag subsidies, direct and indirect, were justified for over the next 30 years or so on the basis of helping farmers return to or maintain parity, defined by pre-WWI price relationships. These subsidies were by the the 1960s receiving heavy critical fire all along the political spectrum, and although the critics didn't manage to stop the subsidies (which are still very much with us in ...