Title: Seasonal adjustment without revisions
Authors: Barend Abeln - Investment consultant (Netherlands) [presenting]
Abstract: Seasonality in macroeconomic time series can `obscure' movements of other components in a series that are operationally more important for economic and econometric analyses. A seasonal adjustment program called CAMPLET, an acronym of its tuning parameters, is presented, which consists of a simple adaptive procedure to separate the seasonal and the non-seasonal component from an observed time series. Once this process is carried out there will be no need to revise these components at a later stage when new observations become available. We compare and contrast CAMPLET with X-13ARIMA-SEATS. The main features of CAMPLET are described, and a brief review of X-13ARIMA-SEATS was provided. We evaluate the outcomes of both methods in a controlled simulation framework using a variety of processes. We apply CAMPLET and X-13ARIMA-SEATS to three time series: U.S.non-farm payroll employment, operational income of Ahold and real GDP in the Netherlands. The main findings are that both methods generally produce similar seasonal adjusted figures.