Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This paper proposes and analyzes a model of how the behavior of voters and that of potential party activists together determine party membership and the ideological characteristics of party platforms. Membership decisions are based on expressive motivations, whereas platforms are chosen strategically. Part of the ideological spectrum may remain outside both parties because of alienation or indifference. Copyright 2003 by Kluwer Academic Publishers