Interesting metric would be the number of people who posted at least one content item every month for past quarter. Here the content item = status/+1/like/comme

Interesting metric would be the number of people who posted at least one content item every month for past quarter. Here the content item = status/+1/like/comment/photo/URL. Write metric is more robust than read metric, especially against users who are simply using FB or G just to login into other sites or apps.