Variance formula

[Mr_J]

Can someone give me a variance forumla that I can copy into an excel spreadsheet, ie chance of experiencing a certain run or worse over X hands?

I did do a search, most of it seemed to be directed to chance of being a winning player etc. I read one of the mod's posts that goes into this, but I think I got a part wrong.

Anyway this is what I'm doing, where am I going wrong??

=(R-(H/100*WR))/(SD*SQRT(100))

is to get the fraction to put into =NORMSDIST(X/Y)

which should give the odds of running that bad or worse.

H = total hands.
WR = expected BB/100
SD = SD/100
R - +/- BB (ie the run)

Eg
1000 hands
2bb/100
15 SD/100
-50 bb run

=(-50-(1000/100*2))/(15*SQRT(100))

Which gives a fraction of -7/15, put it in:

=NORMSDIST(-7/15)

Which gives 32% chance of a 2bb player being -50bb or worse after a 1000 hand sample (lol).

I couldn't find a formula in the search so put that together based on what of the mods wrote. It'd be nice if something corrected it for me or gave me an actual forumla I could use.

[BruceZ]

[ QUOTE ]
Eg
1000 hands
2bb/100
15 SD/100
-50 bb run

=(-50-(1000/100*2))/(15*SQRT(100))

[/ QUOTE ]

Should be:

=(-50-(1000/100*2))/(15*SQRT(1000/100)) =~ -1.476

=NORMSDIST(-1.476) =~ 7.0%

[Mr_J]

Thanks [img]/images/graemlins/smile.gif[/img]