More on the methodology here: <a href="http://intelligenceengine.blogspot.com/2014/11/game-outcomes-project-methodology-in.html" rel="nofollow">http://intelligenceengine.blogspot.com/2014/11/game-outcomes...</a><p>tl;dr it's very similar to the DORA report, though they had an external reference point in the form of metacritic scores.