Prices, Plant Size, and Product Quality

Drawing on uncommonly rich and representative data from the Colombian manufacturing census, this paper documents new empirical relationships between input prices, output prices, and plant size and proposes a model of endogenous input and output quality choices by heterogeneous firms to explain the observed patterns. The key empirical facts are that, on average within narrowly defined sectors, (1) larger plants charge more for their outputs and (2) larger plants pay more for their material inputs. The latter fact generalizes the well-known positive correlation between plant size and wages. Similar correlations hold between prices and export status. We show that the empirical patterns are consistent with a parsimonious extension of the Melitz (2003, "The Impact of Trade on Intra-Industry Reallocations and Aggregate Industry Productivity," Econometrica, 71, 1695-1725) framework to include endogenous choice of input and output quality. Using a measure of the scope for quality differentiation from Sutton (1998, Technology and Market Structure: Theory and History. Cambridge: MIT Press), we show that differences across sectors in the relationships between prices and plant size are consistent with our model. Available evidence suggests that differences in observable measures of market power do not provide a complete explanation for the empirical patterns. We interpret the results as supportive of the hypothesis that quality differences of both inputs and outputs play an important role in generating the price-plant size correlations.