Initial estimates of aggregate output and its components are based on very incomplete source data, so they may not fully capture shifts in economic conditions. In particular, if those estimates are based partly on trends in preceding quarters, provisional estimates may overstate activity when...

Forecasts by rational agents contain embedded initial and terminal boundary conditions. Standard time series models generate two types of long-run "endpoints"---fixed endpoints and moving average endpoints. Neither can explain the shifting endpoints implied by postwar movements in the...