• by Erik Sass , Staff Writer @eriksass1, July 3, 2012

After its high-profile dumping in May, Facebook wants to win back GM as an advertiser, according to the Wall Street Journal, which reports that Facebook global sales boss Carolyn Everson met with GM marketing chief Joel Ewanick in Cannes last month to present the social network’s case.

Everson reportedly told Ewanick that Facebook is willing to help GM with “better data” for measuring ROI on its social media investments, going some distance to meeting GM’s original demands, but GM is said to still be skeptical.

The sum spent by GM on Facebook advertising -- $10 million in 2011 -- is quite small relative to GM’s total ad spending and Facebook’s total revenues, but the split was nonetheless important at a symbolic level, as one of the world’s largest carmakers turned its back on the world’s largest social network.

After GM withdrew its advertising Facebook scrambled to produce data showing that social media marketing really does work. In June it released the second part of a two-part report, titled “The Power of Like,” drawing on data on earned media exposure from comScore Social Essentials and ad effectiveness data from comScore AdEffx, along with internal analytics from Facebook. The report aimed to show advertisers how to go beyond simple and less-meaningful metrics like fan acquisition by breaking down social media marketing into three core elements: “fan reach,” “engagement,” and “amplification.”

These three elements work together sequentially to drive sales. For example, in the “fan reach” phase, an advertiser might reach fans with brand messages in their news feed. In the second phase, “engagement, “ the fans talk about this news feed content, and in the third phase, “amplification,” the news feed content spreads to friends, resulting in earned media. Earned media can then be correlated with, among other things, e-commerce or in-store sales.