Lukas Nord, European University Institute (Job Market Seminar)

"Shopping, Demand Composition, and Equilibrium Prices"

Abstract

This paper develops an equilibrium theory of expenditure inequality and price dispersion, to study how retail prices respond to households' shopping behavior. Heterogeneity in the effort to search for prices implies that the price elasticity faced by retailers depends on the composition of demand. For a search market with price posting, I show analytically that retailers optimally charge higher markups if goods are mainly consumed by low-search-effort households. Additional predictions on the shape of posted price distributions are consistent with evidence from US supermarket scanner micro-data. I embed search for prices into an incomplete markets model with non-homothetic preferences and equilibrium price dispersion for multiple varieties. Endogenous heterogeneity in search effort allows the model to match evidence on differences in prices paid for identical goods and reduces inequality in consumption relative to expenditure. I show that the equilibrium response of posted prices across products doubles this direct effect of search on inequality. In addition, the model reconciles conflicting evidence on the cyclicality of retail markups, as aggregate shocks change the composition of demand. Finally, I find that the response of posted prices to a redistributive earnings tax compensates top earners for up to 14% of their losses.

Contact person: Søren Hove Ravn