Temporal influence over the Last.fm social network
Several recent results show the influence of social contacts to spread
certain properties over the network, but others question the
methodology of these experiments by proposing that the measured
effects may be due to homophily or a shared environment. In this
paper we justify the existence of the social influence by considering
the temporal behavior of Last.fm users. In order to clearly
distinguish between friends sharing the same interest, especially
since Last.fm recommends friends based on similarity of taste, we
separated the timeless effect of similar taste from the temporal
impulses of immediately listening to the same artist after a friend.
We measured strong increase of listening to a completely new artist in a few hours period after a friend compared to non-friends representing a simple trend or external influence.
In our experiment to eliminate network independent elements of taste, we improved collaborative
filtering and trend based methods by blending with simple time aware recommendations based on the
influence of friends. Our experiments are carried over the two-year
"scrobble" history of 70,000 Last.fm users.