If you are a brand on Facebook these are the 7 most important metrics that you should be tracking.
1) Engagement- This is the unique # of people who liked, commented, clicked or shared your posts. Keeping people engaged is the #1 way to enhance your visibility organically on Facebook.
2) Post Reach- The number of people who saw your posts. Likes, Comments, and Shares all increase your post reach.
3) Total Reach-The number of people who saw any activity from your page including posts, posts by other people, Page like ads, mentions, and check-ins.
4) Net Likes: What Changed: Likes – unlikes = net likes. Unlikes, Organic Likes, & Paid Likes should all be tracked on different levels.
5) Where Your Page Likes came From: The number of times your Page was liked, broken down by where it happened. Was it ads, sponsored stories, page suggestions, search, or another source? Knowing where your likes are coming from is vital in your overall Facebook strategy.
6) Hide, Report as Spam, and Unlikes should all be tracked closely, as these actions will decrease the number of people you reach.
7) Page and Tab Visits: The number of times each of your Page tabs was viewed. This can give you a better idea of what your audience is looking at.