Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We analyze a series of trials that randomly assigned Wikipedia users in Germany to different web banners soliciting donations. The trials varied framing or content of social information about how many other users are donating. Framing a given number of donors in a negative way increased donation rates. Variations in the communicated social information had no detectable effects. The findings are consistent with the results from a survey experiment. In line with donations being strategic substitutes, the survey documents that the negative framing lowers beliefs about others’ donations. Varying the social information, in contrast, is ineffective in changing average beliefs.