Outlook for Air Transport to the Year 2015 - FILT CGIL Foggia

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Appendix 1ECONOMETRIC MODELS OF DEMANDFOR WORLD SCHEDULED AIR TRAFFICThe basic model form assumed was:y = a x 1b 1 x 2b 2For the model of passenger traffic:y= passenger-kilometres performed (PKPs)x 1 = gross domestic product in real terms (GDP)x 2 = passenger revenue per passenger-kilometre in real terms (PYIELD)For the model of freight traffic:y= freight tonne-kilometres (FTKs)x 1 = world exports in real terms (EXP)x 2 = freight revenue per freight tonne-kilometre in real terms (FYIELD)The a, b 1 and b 2 are constant coefficients whose values were obtained by statistical estimation, using econometricanalysis. The b 1 and b 2 are equal to the elasticities of demand with respect to the corresponding x 1 and x 2 .Annual data were used in the estimations, covering a period of 22 years for the passenger model and 42 years forthe freight model. The data for the CIS are excluded from the freight model. ICAO and the IMF were the sourcesfor the airline and general economic data, respectively, used in the models.Estimated passenger model:ln PKP = 4.63 + 1.34 ln GDP 0.58 ln PYIELD R 2 = 0.975(2.9) (1.7)Estimated freight model:ln FTK = 0.37 + 1.58 ln EXP 0.37 ln FYIELD R 2 = 0.997(21.4) (5.7)The figures in brackets are the “t” values of the corresponding coefficient estimates. The “t” value correspondingto a particular coefficient estimate is a statistical measure of the confidence that can be normally placed in theestimate.47
48 Outlook for Air Transport to the Year 2015It should be noted that the “t” value corresponding to the yield in the estimated passenger model is less than 2. Ingeneral, the larger the magnitude of the “t” value, the greater the statistical significance that can be placed uponthat value. However, a low “t” value does not necessarily imply that the model is not suitable for forecastingpurposes, as in the case here. The values of the coefficients derived from the econometric analysis are relative andnot absolute as bias and variance among coefficients always exist because explanatory variables are not alwaysmutually independent. The R 2 value of 0.975 for the estimated passenger model indicates that the major part ofthe variation of the dependent variable, in this case PKP, has been accounted for and explained by the model. Inaddition, in order to measure the effectiveness of the forecasting application, the actual historical results werecompared with those that were predicted from the model and found to be satisfactory.___________________
Page 2: FOREWORDIntroduction1. This circula
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Page 27 and 28: Chapter 3WORLD ECONOMIC ENVIRONMENT
Page 29 and 30: Chapter 4AIRLINE FINANCIAL TRENDSOP
Page 47 and 48: Chapter 6FORECASTS OF AIRCRAFT MOVE
Page 50: Chapter 6. Forecasts of Aircraft Mo
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Outlook for Air Transport to the Year 2015 - FILT CGIL Foggia

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