I came across this video which explains the findings of a recent study done by Duncan Watts, a sociology professor at Columbia University, on how aggregate data and how it is presented can affect the way people make decisions on social networking sites.
For part of the experiment, two different groups viewed song lists on two different websites. Users were able to download and view songs on the first list, but there was no information or ratings on it. On the second website, the number of times each song was downloaded was displayed to users as aggregate data.
This is an interesting concept in terms of market research. How are consumer decisions affected when there a social influence is present? View the video below: