Chen, Yan, et al. "Social comparisons and contributions to online communities: A field experiment on movielens." American Economic Review 100.4 (2010): 1358-1398.

This field experiment investigates the impact of social comparison on contributions to an online community, specifically focusing on the effect of sharing behavioral and outcome information related to user activity. The study reveals that informing users of the median number of movie ratings significantly boosts contributions by those below the median, with a 530% increase in movie ratings, while causing a 62% reduction among users above the median. Additionally, when above-average users are informed about the average user's net benefit score, they tend to engage more in helpful activities towards others. The results highlight the potential of personalized social information to enhance public goods provision within online communities.