Social Comparisons and Contributions to Online Communities: A Field Experiment on MovieLens

Abstract

We design a field experiment to explore the use of social comparison to increase contributions to an online community. We find that, after receiving behavioral information about the median user's total number of movie ratings, users below the median demonstrate a 530 percent increase in the number of monthly movie ratings, while those above the median decrease their ratings by 62 percent. When given outcome information about the average user's net benefit score, above-average users mainly engage in activities that help others. Our findings suggest that effective personalized social information can increase the level of public goods provision. (JEL C93, H41, L82)

Group payoffs as public signals

“…As mentioned earlier, we have a measurement of group attachment, in the third stage of the experiment, based not on behavior, but on explicit statements of subjects (as in Yamagishi and Kiyonari (2000)). If the display of group payoffs had a substantial effect on group identity, 13 We are aware of four studies that present a statistic on some variable(s) (Bohnet and Zeckhauser (2004), Frey and Meier (2004), Hargreaves Heap andZizzo (2009), Chen, Harper, Konstan, andLi (2010)). With the exception of the study by Hargreaves Heap and Zizzo (2009), the other three studies are not group-based.…”

Towards Adaptive Recruitment and Engagement Mechanisms in Social Systems

“…-broadcasting a message asking for specific contributions [1,5], -asking specific people to do specific tasks [1,4], -emphasizing uniqueness of the user's contributions [1,12], -providing social information and feedback [3,13], -assigning people to groups and setting group competitions [1,7], -setting personal or group goals [1,7,18], -reducing the effort required to identify tasks that are likely to be done by a user (i.e. recommend possible tasks that match the user's interests) [9,5].…”

“…A more recent article [3] also reported experimental studies on MovieLens. The experiments tested the effect of displaying different kinds of social information about users with different levels of participation and different competitiveness profiles.…”

“…Researchers have explored different ways to determine what motivates users to contribute and how to increase their levels of contribution. Previous research projects have mostly drawn from Social Psychology, Sociology and Economics [1,13,9,5,3,18,4] theories. The experimental studies evaluate the impact of engagement mechanisms that embed the principles of the theories.…”

“…Experiments that tested the effect of displaying social information [3] showed that below-median contributors in a community increased their contribution at a higher rate than median and above-median contributors when exposed to social information. Furthermore, this effect was more significant for those users who present a more competitive psychological profile.…”