It is increasingly common for online communities to rely on members rather than editors to contribute and moderate content. To motivate members to perform these tasks, some sites display social comparisons, information designed to show members how they compare to others in the system. For example, Amazon, an online book store, shows a list of top reviewers. In this study, we investigate the effect of email newsletters that tell members of an online community that their contributions are above, below, or about average. We find that these comparisons focus members’ energy on the system features we highlight, but do not increase overall interest in the site. We also find that men and women perceive the comparisons very differently.

This paper evaluates whether social comparison in an online community affects members' inclination to visit and contribute as well as whether the members themselves believe they are motivated by social comparison. This research is conducted through an e-mail newsletter that was sent to a randomly selected sample of members of a movie recommendation social software website named, MovieLens. The weekly newsletter contained social comparison information specific to the recipient (i.e. you have rated [more|fewer|about as many] than the median). It was found that members were more inclined to contribute more (rate more movies) due to this social comparison information. However, some members became more focused on rating movies and contribution to other areas within MovieLens declined as a result. It was also identified that males were more motivated to contribute from social comparison than women.

• Free-riding
• Public good (websites built by member contributions)
• Social influence
• Social upwards and downwards comparison
• Feedback interventions
• Economic theory of inequality aversion
• Propensity to click
• Propensity to act
• Impacts of motivation mechanisms for different genders