Unobserved components (UC) models are widely used to estimate stochastic trends in macroeconomic time series, with the existence of a stochastic trend typically motivated by a stationarity test. However, given the small sample sizes available for most macroeconomic variables, standard Lagrange...

In the aftermath of the global financial crisis, competing measures of the trend in macroeconomic variables such as US real GDP have featured prominently in policy debates. A key question is whether the large shocks to macroeconomic variables will have permanent effects—i.e., in econometric...