pokertracker/STDEV calc

[JinX11]

A quick question about how pokertracker calculates stdev/hr and stdev/100 Hands...currently, the value it calculates and the value MS Excel calculates when I export my session data is fairly different.

When I export my session-by-session detail data (from the Session Notes tab) into Excel and run the STDEV function on BB/Hr. and BB/100 Hands columns, I get different STDEV values (larger).

For instance, pokertracker calculates my STDEV for August to be 14.15 BB/hr, but Excel calculates it to be 21.47 BB/hr.

Any ideas on what I'm doing wrong (besides having too high a STDEV)? Thanks, in advance.

[MarkD]

I have no way to confirm this but I assume pokertracker uses this (http://twoplustwo.com/mmessay8.html) method when calculating your SD and the method in that essay will yield a different result than the SD function of Excel.

The proof for that formula (limited proof IMO) is in Gambling Theory and Other Topics by Malmulth. This is the accepting formula for calculating your SD.