The treatment of ‘quality’ in the cost of living index

This paper develops the implications of cost of living index theory for measuring the impact of changes in the availability and prices of goods on a household's welfare. It considers both the ‘goods approach’, which treats each variety as a separate entity, and two characteristics approaches: ‘L-characteristics’ and ‘H-characteristics’. L-characteristics are Lancaster's ‘linear and additive’ specification; H-characteristics are Houthakker's ‘heterogeneous’ specification in which the household consumes only a single variety of each product. The paper concludes by discussing the implications of the theory for actual index number construction and relating it to the literature on ‘quality’ and ‘hedonic indexes’.