The nature of monetary policy during the 1970s is evaluated through the lens of a forward-looking Taylor rule based on perceptions regarding the outlook for inflation and unemployment at the time policy decisions were made. The evidence suggests that policy during the 1970s was essentially indistinguishable from a systematic, activist, forward-looking approach such as is often identified with good policy advice in theoretical and econometric policy evaluation research. This points to the unpleasant possibility that the policy errors of the 1970s occurred despite the use of a seemingly desirable policy approach. Though the resulting activist policies could have appeared highly promising, they proved, in retrospect, counterproductive.

We examine the reliability of alternative output detrending methods, with special attention to the accuracy of real-time estimates of the output gap. We show that ex post revisions of the estimated gap are of the same order of magnitude as the estimated gap itself and that these revisions are highly persistent. Although important, the revision of published data is not the primary source of revisions in measured output gaps; the bulk of the problem is due to the pervasive unreliability of end-of-sample estimates of the trend in output. Multivariate methods that incorporate information from inflation to estimate the output gap are not more reliable than their univariate counterparts.