  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.
