SIMPLIFIED FORMULAE FOR ESTIMATION OF TREND AND SEASONAL EFFECTS

Usually, for estimation of trend and seasonal effect, one applies rough formulae from general regression model. More explicit formulae can be found in many papers by Z. Zielinski. In this note some useful simplifications of these formulae are derived. This enables us to make all computations on the usual pocket calculator. Our results are illustrated by the example of the monthly data concerning air transport of passengers in Poland from 2000 to 2005.