Car quality improvements and price indices in Spain

The main goals of this study are to measure quality improvements in automobile sector in Spain and to estimate the quality bias in car price index released by INE. In order to do that, we propose an alternative methodology to estimate hedonic regressions. This methodology involves classifying the "indicators" of quality of an automobile in "sub-indices" that reflect different aspects of quality, subsequently grouping the sub-indices in an overall quality index. Consequently, car quality can be measured by a readily interpretable index; and its price can be estimated with statistical accuracy in an hedonic regression where the overall quality index is used as regressor. Results indicate that the implicit quality bias in the car price index released by INE is 3.1 % per year.