View Full Version : Probabilty of PT notes

12-16-2004, 05:08 PM
Dont know if this has been discussed before, but im a little curious, how many hands do you need with someone in Pokertracker before the numbers actually means something?

And, what's the probability of someone having, say, vpip of 30 and i have him on 300 hands, that he actually is a bit on the loose side? Do you need more hands, or maybe less? Does the different notes (like aggression, etc.) require different samplesizes to make sense? You know, that kind of stuff. =)

12-16-2004, 05:51 PM
Depends on what the statistic is. Take VPIP for example. If your opponent's true VPIP is p, then after n hands his sample VPIP (the thing you have in PT) has a binomial distribution with standard deviation sqrt(p*(1-p)/n).

Let's try plugging in some numbers. Say his true VPIP is .2, and you have 100 hands of data on him. Then the SD of your sample statistic is sqrt(.2*.8/100) = .04. This means that 95% of the time you will observe a VPIP between .12 and .28 for a player whose true VPIP is .2, given 100 hands of data.

After 300 hands the SD drops to about .02, so you'd expect to observe between .16 and .24.

Practically speaking, you can conclude that a few hundred hands is a reasonable sample size for getting pretty accurate estimates, and even 100 hands will give you a ballpark figure.


12-17-2004, 12:18 AM
Oh, thanks for the reply. One day i will grow up and learn math too.

What other stats are useful after 100 hands, would you say? Aggression? Preflopraise? I guess went to showdown/won at showdown requires more hands...