Estimating BB/100

[indianaV8]

I have two questions.

If I want to find out BB/100h range, and I know the STD, I estimate the range boundaries (with given confidence level, e.g. for 95% z = 1.96) by the formula:
z*(STD/sqrt(N))
where N is the number of hands.

Now the questions are:

1) What if I don't know the STD? If I have played 20k hands, but I don't know what the STD is (and I calculate it from this 20k sample). Is the above formula still correct?

2) What if the distribution is not normal? Do one gets better results if the outcomes of each event are very limited, e.g. jam/fold case you either fold (ev=0), fold BB (ev = -BB), or you go allin (EV +- yourstack). Does this has anything to do in the above formula, or in the above formula the mean (BB/100) will follow normal distribution in any case?

Thanks

P.S. Any digestable links/references for are also appreciated ...

[jay_shark]

1) sample mean +- z*(s.d of sample mean) . What is your sample mean in terms of bb/100 over a 20k sample ??

You can calculate your standard deviation given at least 30 sessions where one session can be regarded as 100 hands . So 3000 hands would suffice and you would use the formula

s.d of sample mean = s.d/sqrt(30) .

It should be approximated by a normal distribution after 3k hands .