Is the Quantity Theory of Money Useful in Forecasting U.S. Inflation?

We propose a new simple model incorporating the implication of the quantity theory of money that money growth and inflation should move one for one in the long run, and, hence, inflation should be predictable by money growth. The model fits postwar U.S. data well, and beats common univariate benchmark models in forecasting inflation. Moreover, this evidence is quite robust, and predictability is found also in the Great moderation period. The detected predictability of inflation by money growth lends support to the quantity theory.