Causality and the independence phenomenon: The case of the demand for money

We examine the demand for money using causality results with data from two alternative policy regimes. For Spanish series of money and prices we obtain the same result of independence that Feige and others found with U.S. data. The result of the test for the German hyperinflation period reveals bidirectional causality. It is shown that the somehow striking results of widespread independence among economic time series do not disprove but rather confirm the existence of a true underlying causal relationship. Causality results, and independence in particular, give us testable restriction for the structural form. In the case of models for expectations in the rate of inflation, these restrictions allow us to revalidate the stability of the demand for money as postulated by the Quantity Theory.