Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Over the period 1953-83, twelve accounting measures of profitability, which are not on average highly correlated, imply measures of the profitability advantage of large firms that move closely together. All twelve measures decline significantly and substantially over this entire period; there is no acceleration in the 1970s. All measures move countercyclically. Together with recent work on the dynamics of the interindustry concentration-profitability relation, these results point to the existence of important procyclical industry-level changes in the strength of the concentration-profitability relation. Copyright 1989 by Blackwell Publishing Ltd.