Determinants of the Increase in the Number of Interest Groups in Western Democracies: Theoretical Considerations and Evidence from 21 OECD Countries

Mancur Olson's theory of institutionalsclerosis is based on the notion that thenumber of interest groups within a countryincreases with the duration of itspolitical stability. The following paperargues that the increase in the number ofinterest groups over time could also be aconcomitant of economic development.Theoretically, both explanations provetenable. An empirical cross-sectionalregression analysis using data from 21OECD countries finds no evidence for asignificant impact of the duration ofpolitical stability on the number ofinterest groups. A significantly positiveeffect is, however, reported for the degreeof economic development.