Poker math related to downswings and ptbb/100

[Belok]

It has been a long time since I have done any calculus, so I cannot remember how to set up the equation to predict how plausible it would be for this to happen, but here goes...

I have a friend, who I believe is a marginal winner at 100 and 200$ NL full ring. He has recently been in a wicked downswing, and I am pretty sure he is not playing anywhere near his A-game. But he refuses to believe that the downswing is a result of anything but an awful series of beats.

Can anybody who knows how to do this calculation plug these #s in for me and try to help me figure out how to explain that this downswing is a result of bad PLAY as well as bad cards?

I dont know his exact #s because he does not use pokertracker. I can fairly well estimate them though.


SD = 30ptbb per 100 hands
This is a fairly reasonable expectation for a tight aggressive style player. He is a bit more passive preflop than I am, so this number could be as high as 35 or 40.

PTBB/100 = 1
I am completely unsure of this. I know he is a winner long term, but not by a whole lot. He puts in a TON of hands though, so this should be a pretty good guess.

Approximately 50,0000 hands played in august.

Down 30 buyins, or 1500ptbbs.

so our numbers are
SD = 30 per 100hands
Win Rate = 1ptbb/100
Actual earn = -1500ptbbs
Hands played = 50,000

Looking for what % chance a +EV player could have a downswing this massive.

If we need more information, let me know.

Also, if someone happens to be bored and would like to plug these #s in for me. At what win rate does a downswing of this magnitude become a reasonable expectation? Say within 3SDs.

Thanks for the help [img]/images/graemlins/smile.gif[/img]