Is there more than one critical concentration ratio? An empirical test for the Portland cement industry

Audit market structure and related changes in Taiwan: the effects of CPA qualification changes and mergers

“…If we choose the HHI of the biggest five accounting firms, it can be denoted as HHI5. Azzam et al (1996) pointed out that when HHI = 0, it suggests a perfect competition, and when HHI = 1, it suggests a monopoly. When the market is a pure monopoly, it means only one company exists and the indicator is 1.…”

Corporate Environmental Citizenship Variation in Developing Countries: An Institutional Framework

“…Studies show that an industry may be essentially competitive but become effectively collusive beyond a certain level of concentration. This is known as the critical concentration ratio, CCR (Azzam et al, 1996;Bradburd and Over, 1982). For example, Bain (1951) found a CCR 8 of 0.7 in American manufacturing industry.…”

Long-Term Medicaid Excess Payments from Alleged Price Manipulation of Generic Lorazepam

“…Searching for a critical concentration ratio has intrigued many scholars in industrial-organization economics over the years, although there seems to be no "one size fits all" that antitrust authorities can rely on for every market. [30][31][32][33] Moreover, the notion of a critical concentration ratio may be more realistic than assuming a smooth transition between monopoly and competitive pricing. In 1997, the year before the generic lorazepam price rise, CR 4 Empirical evidence strongly suggests substitution difficulty.…”