Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We aim to empirically investigate the rationale of in-group-favoritism. As potential explanations, we concentrate on intrinsic preferences for own-group members and motivations related to individuals caring about the beliefs of others (founded on guilt aversion). We also consider their intersection. Our evidence shows that in-group-favoritism cannot be accounted for by changes in expectations. This suggests that preferences per se are the most powerful explanation of social identity.