[jason1990]

Poker Tracker does not calculate standard deviation correctly. It uses only the results of each session, and not the results of each hand. This has two effects. The major effect is that the SD it calculates can be grossly inaccurate if the number of sessions is not large. The secondary effect is that the SD it calculates can be biased if session length is at all correlated to the session winnings.

If you want to correctly calculate the sample standard deviation of the alleged cheater, then you must compile an Excel spreadsheet that contains the results (in BBs) of each hand played by the alleged cheater. If you have 500 hands played by the accused, then you will have a column of 500 numbers. The sum of these numbers will be the total BB won by the accused. The average of these numbers will be his sample winrate in BB/hand. Multiply that by 100 to get his winrate in BB/100.

Now use Excel's STDEV function on this column of data. The result will be his sample standard deviation in BB/hand. Multiply it by 10 to get his SD in BB/100.