When it comes to Facebook marketing, an overly narrow definition of engagement can mask the value of earned media, according to a report released recently by Wildfire Interactive.

Engagement in the form of clicks is great, of course, according to Wildfire's analysis. But the best performance comes from earned media. The study divides Facebook media into three types: Owned media are fan pages, and brands use paid media to drive traffic to them. Earned media include mentions, recommendations and shares generated by users.

The study found that earned media can create a 12 percent increase in all engagement rates, and it also converts new users.