Taha Yasseri of the University of Oxford, in 2013, studied the statistical trends of systemic bias at Wikipedia introduced by editing conflicts and their resolution.[218][219] His research examined the counterproductive work behavior of edit warring. Yasseri contended that simple reverts or "undo" operations were not the most significant measure of counterproductive behavior at Wikipedia and relied instead on the statistical measurement of detecting "reverting/reverted pairs" or "mutually reverting edit pairs". Such a "mutually reverting edit pair" is defined where one editor reverts the edit of another editor who then, in sequence, returns to revert the first editor in the "mutually reverting edit pairs". The results were tabulated for several language versions of Wikipedia. The English Wikipedia's three largest conflict rates belonged to the articles George W. Bush, anarchism, and Muhammad.[219] By comparison, for the German Wikipedia, the three largest conflict rates at the time of the Oxford study were for the articles covering Croatia, Scientology, and 9/11 conspiracy theories.[219]
