Constructing confidence bands for the Hodrick--Prescott filter
By noting that the Hodrick--Prescott (H--P) filter can be used as the solution to a particular regression problem, we are able to show how to construct confidence bands for the filtered time-series. This procedure requires that the data are stationary. The construction of such confidence bands is illustrated using annual US data for real value-added output and monthly US data for the unemployment rate.