A new NPD Group study finds that active Twitter users buy 77 percent more digital music downloads on average than non-users. Additionally, 12 percent of those who have bought music in the last three months also report having used Twitter, versus 8 percent of overall Web users.

“Based on their music-purchasing history, active Twitter users are simply worth more to record labels and music retailers than those who are not using Twitter,” says NPD entertainment analyst Russ Crupnick.

A third of all Twitter user reported buying a CD in the prior three months, and 34 percent reported buying music digitally, compared to 23 percent and 16 percent for overall Web users. Another one-third of Twitter users listened to music on a social networking site, 41 percent via online radio and 39 percent watched music videos online. Overall, they are twice as likely than average Web users to visit MySpace Music and Pandora.

“Twitter has the potential to help foster the discovery of new music, and improve targeted marketing of music to groups of highly-involved and technologically savvy consumers, but it has to be done right,” Crupnick said. “There must be a careful balance struck between entertainment and direct conversation on one hand, and marketing on the other. Used properly Twitter has the power to entertain — and to motivate music fans to purchase more new albums, downloads, merchandise, and concert tickets.”