Facebook has changed the way it calculates the total monthly and daily active users (MAU and DAU) for apps on the social network, sending figures plummeting.
The adjustment means that users who choose not to authenticate after a permission dialog box is clicked, and those who visit an app but do not log in, will no longer be contribute towards active user counts.
As a result of the changes, some games have seen more than half of their previously reported user figures drop away (though these changes have made no difference to the actual traffic each game sees).
The MAU figure for Zynga's newly-launched Adventure Worlddropped 58 per cent from 39.4 million to 16.4 million. CityVille fell a comparitively more modest proportion, from 76 million to 55 million, while EA's The Sims Social dropped from 65 million to 42 million.
Facebook adjusted its reporting methods in August last year, discounting users who just 'liked' apps from the total count - a change that also saw a drop in MAU and DAU figures for developers.

http://www.next-gen.biz/news/faceboo...igures-plummet