An anonymous reader writes: Joe Doliner has done a statistical analysis of mistakes in rated chess games. He used a chess engine called Crafty, which is capable of not only finding mistakes, but quantifying how bad they are. After crunching all the matches on chessgames.com in 2014, which amounted to almost 5 million moves, Crafry found only 67,175 blunders that were equivalent to a 2-pawn deficit or worse. With a pair of graphs, Doliner shows how mistakes decrease as player rating increases, as you'd expect. According to the trendline, gaining 600 rating points roughly halves the number of mistakes a player makes. He made the data and tools available in a public repository for others to dig into.