Milton Friedman and I have been engaged for some time in a study of the characteristic behavior of the quantity of money over long periods in relation to income, prices, and interest rates m the United States and the United Kingdom. In our study, our observations of levels are the average annual values of each variable during cyclical phases, starting with the expansion phase of 1878–1882 in the United States and 1879–1883 in the United Kingdom, and ending with the final phase that can be marked off for each country, respectively, 1969–1970 and 1968–1969. In all, we have forty-five observations of levels for the United States, and thirtythree for the United Kingdom. In addition to levels of observation, we also examine rates of change, which we express as the slopes of least-squares lines connecting three successive phase averages. For each country, the rate-of-change observations are two fewer than the number of level observations.
The Relation Between Unemployment and the Rate of Change of Money Wage Rates in the United Kingdom, 1861-19571