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

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