Beyond Don's charts?

From Stanford Wong's BJ21

Posted by truefive on 30 Sep 1997, at 9:20 a.m.

Don’s charts for risk of ruin and bankroll requirements are great. All you need is the standard deviation and ev per round and you’re there. But the charts top out at an ev of .05 and a std of 4.0. Could I please get some help with determining results with numbers that go beyond this. With unusually high bet spreads std can be much higher than the charts would be useful for. Is the best way to use a formula and plug in the numbers?

For reasons that don’t need to take up space here a friend is playing with unusually large bet spreads. He just completed a trip in which he played about 50 hours and lost a total of 30 TOP bets (not units). He is concerned and wants to know exact numbers on ror and bankroll requirements. We both would like to know how to figure it out for ourselves if the numbers fall outside the parameters of the charts.

Here are the numbers:

expectation per round = .2069

std per round = 26.89

The reason for the huge std is that the player is betting fairly high stakes at high true counts but only $5 down to a certain negative true (don’t ask). The numbers above have already been adjusted to per 100 numbers to allow for the hands observed without bets below the designated negative true.
Could someone, using this example, please teach us to figure out bankroll requirements for particular risks of ruin and vice versa.

Don, feel free to post charts through std 30. (<:

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