Facebook Page Statistics: Here are the statistics you need to measure and how to measure them to determine your Facebook Page’s performance.
Good article by Social Media Examiner! but appearantly they forgot that Facebook insights do not provide anymore the so called "Lifetime Post reach by people who like your page" even in post level insights , Facebook only provides : Organic – Viral – Paid and total reach insights ! I guess Facebook is advised to reconsider featuring this measurement again
See on www.socialmediaexaminer.com