9.1 PARSIMONIOUS MODELS FOR SEASONAL TIME SERIES9.2 REPRESENTATION OF THE AIRLINE DATA BY A MULTIPLICATIVE (0, 1, 1) × (0, 1, 1) 12 MODEL9.3 SOME ASPECTS OF MORE GENERAL SEASONAL ARIMA MODELS9.4 STRUCTURAL COMPONENT MODELS AND DETERMINISTIC SEASONAL COMPONENTS9.5 REGRESSION MODELS WITH TIME SERIES ERROR TERMSAPPENDIX A9.1 AUTOCOVARIANCES FOR SOME SEASONAL MODELS