Indirect seasonal adjustment of some aggregate Croatian economic time series

There are two approaches to seasonal adjustment of an aggregate time series: direct and indirect one. Direct seasonal adjustment is obtained by applying the seasonal adjustment to the aggregate series, while indirect adjustment is aggregation of seasonally adjusted subcomponents. Except under very restrictive conditions, these two approaches usually produce different results. In this paper some of aggregate economic time series of the Croatian Central Bureau of Statistics were directly and indirectly seasonally adjusted using TRAMO/SEATS, X-12-ARIMA and DAINTIES. The aim of this paper is to investigate differences between growth rates in the direct and indirect adjusted series. Growth rates are very important pieces of information in the analysis of economic activity. It can be concluded that the indirect approach should be preferred, especially if components of aggregate series do not have similar seasonal properties.