The Optimal Measure of Concentration

Abstract Most objections to the use of simple discrete concentration measures note that such measures fail to take into account the number and individual sizes of firms in an industry. Proponents of the use of cumulative concentration ratios (Herfin-dahl, etc.) contend that if individual firm-size information were available, superior results would be obtained. In assessing the validity of these objections, the authors find that (1) no one of the standard concentration indexes appears superior to any others; and (2) the number and size distribution of individual firms does not seem to affect materially the results obtained.