Today, Facebook announced that, along with the redesigned permissions dialog it introduced at f8, it’s also making a change to the way it counts active users on canvas applications to only count those who are logged in as active users. This means that users who hit the permissions dialog but choose to not authenticate the app, or who visit the app without logging in (for those apps that allow that behavior), will no longer be included in active user counts.

Thus, because most apps at least have users who see the permission dialog but don’t log in, we are expecting to see a one-time decline in those stats as documented on AppData.com associated with this change. This will appear in AppData starting 15 October. It’s important to note that this change doesn’t correlate to any actual change in traffic to apps. The numbers will now simply no longer include users who don’t log in. Facebook says this change will not affect Connect apps or Page tabs.

Since the Facebook Platform launched in 2007, Facebook has updated the methodology it uses to count active users for platform applications a few times. For example, last August, Facebook tweaked its formula to no longer include people who like or comment on feed items shared by applications. As we said at the time regarding that change, “We think this change to the way Facebook calculates active users for applications makes a lot of sense. People who like or comment on stream content published by an app shouldn’t be counted as active users like canvas page viewers are.”