Although supervised dimension reduction methods have been extensively applied in different scientific fields, they have hardly ever been used in production economics. Nonetheless, these methods can also be useful in regulation of natural monopolies, where firms’ cost and performance are affected by a large number of environmental factors. As economic theory suggests, at the presence of other relevant production or cost drivers, the traditional all-inclusive assumption is not satisfied. This paper shows that purging the data allows us to address this issue when analyzing the effect of weather and geography on efficiency in the context of the Norwegian electricity distribution networks
