# Method to reliably determine abnormal statistical values

I'm searching for a statistical method to determine if a player is cheating in an online game.

Given a number of positive points and a number of negative points per player (score) and given $n$ players ($n <= 64$). Each player can cheat independent of each other. I used standard deviation, which works great on a single player but fails miserably as soon as several players are cheating at the same time.

Is there any useful algorithm or formula for this problem?

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I've posted it to stats.stackexchange.com/questions/4904/…, with further explanations. –  Quandary Nov 25 '10 at 11:25