A vector error-correction model (VECM) that forecasts inflation between the current quarter and eight quarters ahead is found to provide significant leading information about inflation. The model focusses on the effects of deviations of M1 from its long-run demand but also includes, among other things, the influence of the exchange rate, a simple measure of the output gap and past prices.

In out-of-sample forecasts of the eight-quarter inflation rate from 1978 on, the VECM had a mean absolute error of just over one percentage point, and a root-mean-squared error of just under two. From the early 1980s on, mean absolute errors and root-mean-squared errors were both less than one percentage point. In addition, except for 1982, the model performed well around the turning points in out-of-sample experiments.

An interpretation of these results is that monetary disequilibria—represented here as deviations of M1 from its long-run demand—are part of the inflation process. That is, in this model, a "money gap" precedes inflation, and an aggregate money gap persists until prices change to help restore monetary equilibrium.