Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Antitrust regime shifts represented by the 1933 adoption and 1935 annulment of the National Industrial Recovery Act are postulated to have effects analogous to temporary achievement of Bradburd and Over's 'integrative concentration level' (Bradburd and Over, 1982); a level at which cartel formation and maintenance costs are outweighed by collusive spoils. 'Regime switching' analysis of Census of Manufactures data reveals a 'critical concentration level' of 60 percent in 1933, which disappears in 1935, and reemerges at 38 percent in 1937. The empirical results support the Bradburd and Over framework and suggest that temporary shifts in antitrust regimes may have lasting impacts on the ability of an industry to exercise market power. Copyright 1994 by MIT Press.