Facebook has changed in the way it measures and reports the widely cited "active user" numbers for Facebook apps, a move that has reduced the reported user counts for many popular Facebook games.
The new system, unveiled over the weekend, displays statistics based only on the number of app visitors that have "authenticated" the app for use with their account, rather than reporting the total number of visitors an app gets in aggregate.
Developers still have access to both the old "visitor" numbers and the new "authenticated user" numbers through Facebook's tools, but only the latter number is now reported publicly on app pages.
"We believe this shift from 'visitors' to 'authenticated users' more accurately reflects the usage of an application, and it brings our measurement methodology for apps into alignment with how we measure engagement on Facebook," the company said in announcing the move.
The change in methodology shows up in dramatic fashion on major app usage tracker AppData
, which uses publicly provided numbers from Facebook to track app popularity.
Top publisher Zynga, for instance, dropped from an AppData-reported mark of 262.5 million aggregate monthly active users on October 14 to 194.5 million on October 15, a drop of about 25 percent.
Reported usage for apps from other major social game companies showed similar drops across the board, though some apps were hit harder than others by the change.
"While this change will result in a perceived decline in active users for some apps, the number of users actually engaging with an app or playing a game is unaffected by this change," Facebook clarified.
In filing for an upcoming IPO
in July, Zynga reported an aggregate mark of 232 million monthly active users as of June 30, well below the 280 million reported publicly at the time. The company also reported
a "unique" user count of 148 million players at the time, a number that counts players of multiple Zynga games only once.
"We support Facebook's decision to change the way it measures the number of active users of its applications as it more accurately portrays the number of people who play Zynga games," a Zynga spokesperson told VentureBeat