The success of your Facebook Page is dependend on the engagement (likes, comments & fan posts) of your fans. Facebook measures the relevancy of pages with it’s Edgerank algorithm (more info here). Simple put, if fans don’t like, comment or post on your page, Facebook will deem it irrelevant and hide it your fans’ newsfeeds.
Keeping fans engaged also generates organic growth. Fans that like, comment and post on your Page generate newsfeeds in their personal networks, exposing new potential fans to your content.
Facebook’s insights reports how many impressions each of your post generates. At Think! we have a simple target metric for posts on the Fanpages we manage:
When posts generate more impressions than the number of fans, it strongly suggests that the overall engagement of the Page is strong. After all, posts are potentially presented to non-fans. Impressions are not ‘unique’ and one fan could generate multiple impressions.
The formula is not perfect, but we like the simplicity.