Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
In the supply of public goods, far less free riding actually occurs than traditional theory predicts. As one explanation, the social composition function, which aggregates individual contributions into an available social total, may not always take the standard summation form. Theoretical considerations indicate that free riding should be least for a social composition function of the weakest-link type but greatest for the best-shot type. Using a sequential protocol, the authors' experiments strongly confirm theoretical anticipations under all three types of social composition functions. Even under the more onerous sealed-bid (simultaneous play ) protocol, the experimental subjects are able to make some partial progress toward the theoretical ideal. Copyright 1989 by University of Chicago Press.