The stylized facts of macroeconomic time series can be presented by fi
tting structural time series models, Within this framework, we analyse
the consequences of the widely used detrending technique popularised
by Hodrick and Prescott (1980). It is shown that mechanical detrending
based on the Hodrick-Prescott filter can lead investigators to report
spurious cyclical behaviour, and this point is illustrated with empir
ical examples. Structural time-series models also allow investigators
to deal explicitly with seasonal and irregular movements that may dist
ort estimated cyclical components. Finally, the structural framework p
rovides a basis for exposing the limitations of ARIMA methodology and
models based on a deterministic trend with a single break.