Adaptive expectations, rational expectations, and money demand in hyperinflation Germany

Abstract

In the recent literature Sargent and Wallace ( IER, June, 1973) have estimated the demand equation for money in hyperinflation under the restriction that the adaptive formula of Phillip Cagan yields rational inflation expectations in the sense of John Muth. The present paper finds evidence to reject for the Germany case the proposition that adaptive expectations are rational. The procedure employed is basically to overfit the stochastic representation for the inflation rate implied by the ‘adaptive-is-rational’ hypothesis. The paper also puts forward and applies a two-step procedure to estimate the important money demand elasticity in hyperinflation. The procedure returns reasonable results with large estimated standard errors.