Recent research has proposed the state space (88) framework for decomposition of GNP and other economic time series into trend and cycle components, using the Kalman filter. This paper reviews the empirical evidence and suggests that the resulting decomposition may be spurious, just as...

Estimates of the natural or full employment level of real GNP have usually been obtained by statistical detrending procedures which assume independence between trend and cycle. This paper presents an alternative approach which says that the natural level should be measured in the context of a...