A re-evaluation of empirical tests of the Fisher hypothesis

This paper shows that the recent literature that tests for a long-run Fisher relationship using cointegration analysis is seriously flawed. Cointegration analysis assumes that the variables in question are I(1) or I(d) with the same d. Using monthly post-war U.S. data from 1959-1997, we show that this is not the case for nominal interest rates and inflation. While we cannot reject the hypothesis that nominal interest rates have a unit root, we find that inflation is a long-memory process. A direct test for the equality of the fractional differencing parameter for both series decisively rejects the hypothesis that the series share the same order of integration.