Models of product differentiation typically assume a demand for variety. This paper derives the demand for variety in a model where a representative consumer chooses how many specialised varieties to purchase for the pursuit of different activities. In contrast with previous models this...

This paper examines the frequency, pervasiveness and determinants of product switching among U.S. manufacturing firms. We find that two-thirds of firms alter their mix of five-digit SIC products every five years, that one-third of the increase in real U.S. manufacturing shipments between 1972...