FORTUNE — “Be more social” is advice that pretty much every entrepreneur gets. Have a presence on Facebook. Be active on Twitter. But does that translate into sales? It’s complicated.

Recent research about music sales showed a surprising social network generating an increase in sales for artists. Track plays on Last.fm, a music discovery service that has been around for more than a decade, correlate more highly to music sales than Facebook (FB) likes and Twitter follows, according to research from MusicMetric, a firm that analyzes online music… (Fortune Magazine)