Fred Wilson is right

Fred sez: “Social media is no different from all media. The number of people who
at one point were interested in your content or service is not that
meaningful. What matters is the number of people who engage with your
content or service on a daily basis and how engaged they are. And RSS
subscribers, Facebook app installs, and follower numbers don’t measure

Susn sez: Fred is totally bottom line level of right. This is the active versus installed base of any application (as opposed to that other metric, page views for media).and the user to install or registration ratio is always easily 3 to 1, even less over time as people churn out.