Expectations in the German hyperinflation reconsidered

Data on forward foreign exchange rates during the German hyperinflation after World War I provide direct observations of expected changes in the spot rate. Although levels of these forward rates seem to be efficient predictors of the spot rate, the predicted changes in the spot rate are biased downward substantially and do not meet the specific conditions of rationality. Indeed, the bias in the forward rate predictions is similar to bias in adaptive expectations of the spot rate. The behavior of the forward rate can be rationalized as a gradual market adaptation to a new regime of volatile and escalating inflation, reasonably represented by adaptive expectations. The strict definition of rational expectations needs to be broadened to allow for the difficulty of distinguishing between permanent and transitory shocks.