5 Velocity relationships  3  See Friedman (1968, pp. 8–11). At roughly the same time, Phelps (1967) derived similar results using a formal economic model.
4 Another consideration motivating Friedman’s choice of rule was his concern that a more active monetary policy strategy might be difficult to formulate because of the “long and variable lags” in the effect of monetary policy (a term he had coined in Friedman (1948, p. 254)). 5 See Clarida, Galí, and Gertler (1999, Result 10, p. 1687).