Last week, Mashable published an article about the value of a Facebook fan.  This article has been shared thousands of times and reposted all over the marketingverse, and I’m terrified by the implications of how may people have read it (more on that later). Using a CPM model, Vitrue calculated that a Facebook fan is worth $3.60.  Here’s the math: from: Mashable There’s one problem: This is NOT how Facebook works. This statistic reinforces one of the most common misconceptions about social media.  A misconception near-and-dear to people who think in TRPs and GRPs that is so flawed that it threatens to destabilize your efforts on Facebook and potentially reward bad behavior by community managers. This statistic puts a value on 1-way communication and totally overlooks the core of a good Facebook campaign. Engagement When working in social spaces, engagement is key.  Lets say you have a million fans and you post daily.  By some miracle you get a 100% impression rate, but only 5 likes and 5 comments.  The bulk of those million impressions came from people scrolling through their newsfeed where your post is likely sandwiched between posts by friends, other brands and in the worst case scenario a note that a friend has engaged with your competitor.  Few intelligent media buyers would pay $5 CPM for this kind of cluttered and shared text-only inventory. In this case, you had 10 meaningful engagements and a boatload of mediocre impressions, especially since you probably got most of your fans through an engagement block that allowed people to become fans without ever visiting your page.  Your 1MM fans are hardly worth $3.60 a piece at a 0.001% engagement rate.  If you were buying banner inventory and had a 0.001% engagement or click-thru rate, you’d move your money elsewhere, but by Vitrue’s logic each of these fans is still worth $3.60 However, when someone comments on your wall or likes a post or uses an app, their activity is shared on their newsfeed.  All of their friends see someone they know, and hopefully trust, engaging with your brand, which is effectively an endorsement.  Most brand activity in social spaces is not instigated by brands.  It’s people asking their peers for advice, and a personal endorsement is the best you can hope for. So how do you measure