University of Minnesota

music sharing photo

Bookmark and Share (cc) Ian Crowther on Flickr

Social Influence Online

Do friends make friends pay?

Do friends influence one another to buy products, embrace beliefs, and adopt behaviors? The common assumption is they do, but how and to what extent? Whether it’s among family members, peer groups, or social circles, influence is both naturally occurring and something people try to harness and use. It can be incredibly powerful, and equally elusive. University of Minnesota researchers are using the online social graph to measure such fundamental human constructs as influence.

The Study

If two friends buy the same product a week apart, did one friend influence the other’s decision to buy? Or, do they simply have similar taste? Or did they both see a promotion for the product? last fm graphic

Teasing out cause-and-effect evidence of social influence online is challenging when so many alternative explanations are possible. To tackle this question, University of Minnesota researchers Ravi Bapna and Akhmed Umyarov conducted a randomized experiment with, a music-listening social network.

The experiment used a multi-threaded data crawler to track four million users over two years, resulting in a dynamic dataset with more than a billion rows. Testing included a control and treatment group to determine whether or not peer influence was present in the network.

The study showed that when a person becomes a paid subscriber of the service, the odds her friends will buy a subscription increase by 50% due to peer influence. 50 % graphic


This research can help “freemium” businesses convert more users into paid subscribers. The same techniques and finding can help any kind of business develop more effective digital marketing strategies. Beyond product marketing, greater understanding of influence online may change political campaigns, public health education, and societal movements.



Bapna, R., Umyarov, A, 2012, “Are Paid Subscriptions on Music Social Networks Contagious? A Randomized Field Experiment,” National Bureau of Economic Research Summer Institute on the Economics of IT and Digitization, 2012, Cambridge, MA