Thats based on a joint survey conducted by ReverbNation and Digital Music News, one that found that artists now place a disproportionate premium on Facebook Likes. In fact, they not only regard Likes as being three times as valuable as email signups, but they also made similar
comparisons to YouTube channel subscribers and Twitter followers.
As part of the survey, artists were asked to spread 100 points across a variety of social network connections to allocate importance, and this is what resulted.
Source
Posted 12/2011