The decomposition of a given time series into trend, seasonal component, and irregular component is formulated as a minimization problem. The trend is chosen such that it is as smooth as possible; the seasonal component is chosen such that it exhibits a seasonal pattern as stable as possible; and...

The aim of this paper is to develop a model-based seasonal adjustment method which will yield the same decomposition formulas as the descriptive seasonal adjustment procedures proposed in Schlicht/Pauly (1984) and Schlicht (1981). Hence the duality between the descriptive and the model-based...

The seasonal adjustment method proposed by Schlicht (1981) can be viewed as a method that minimizes non-stochastic deviations (perturbations). This interpretation gives rise to a critique of the seasonality criterion used there. A new seasonality criterion is proposed that avoids these...

The paper discusses a new seasonality hypothesis which is one part of a weighted regression approach for the decomposition of a time series into a trend, a seasonal component and an irregular component. It is shown that there exists a regression formulation leading, as in the descriptive...