摘要：Using a maximum entropy technique, we estimate the market shares of each firm in anindustry using the available government summary statistics such as the four-firm concentrationratio (C4) and the Herfindahl-Hirschmann Index (HHI). We show that our technique is veryeffective in estimating the distribution of market shares in 20 industries. Our results providesupport for the recent practice of using HHI rather than C4 as the key explanatory variable inmany market power studies, if only one measure is to be used.
