An instrumented variable approach (two-stage least squares regression) is used to control for price endogeneity, allowing consistent parameter estimation. A set of instruments are found to pass all validity tests, and are offered as instruments that can be used in disaggregate air travel models of demand. The instruments are based on Hausman-type price instruments, which use a firm’s own prices in other markets as instruments for a market of interest, as well as measures of the level of market power by multiproduct firms (as in Stern, 1996). We build the instruments by using prices and flight frequencies from data compiled from an OTA website.
The price coefficient of the 2SLS regression model, which corrected for price endogeneity, is found to be 2.9 times more negative than the price coefficient for an uncorrected model, demonstrating the importance of correcting for endogeneity. For the OLS regression model, the estimated price elasticity of demand (evaluated at the mean of price) is 0.64, which represents inelastic demand. After correcting for endogeneity using 2SLS, the estimated price elasticity of demand is 1.84, which represents elastic demand.
It would be interesting to aggregate our data and/or to mis-specify the model using average prices instead of disaggregate prices. A priori, it is expected that price elasticities from an aggregated model would be less elastic than the price elasticities of our model. This is because on a daily basis, airline customers can choose to purchase departure dates with lower prices, or they can choose a different airline with a lower price offering for the day, or they can wait to purchase when a lower price is offered. This dynamic would not be captured in aggregate data.
We find that the total number of bookings is decreased during ongoing promotional sales of JetBlue’s low cost competitor Virgin America. In future research, it would be interesting to model JetBlue and Virgin America demand together in the same model using a nested logit model to capture the degree of substitution between the airlines. JetBlue and Virgin America are likely to be close substitutes. Incorporating a major carrier into the models could add insight about the substitutability of LCCs versus major carriers.
Also, there is a future research need for incorporating competitor prices into revenue management forecasts. Within the airline industry, there has been growing interest in developing the next generation of revenue management (RM) systems that can more accurately represent how customers make decisions in today’s online environments. The development of these next-generation “choice-based” RM systems require information about the prices (or “choices”) viewed by customers at the time of booking – both on the carrier of interest and, potentially, across several different competitors.
6.7. References
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CHAPTER 7: Conclusions and Future Research Directions
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