Kirk: ROR/Optimal Bankroll

[Kirk]

I'm trying to figure out what my optimal bankroll would be, so that my ROR is around 1-2%. This would be a trip bankroll, where I would spend 4-5 hours playing at each place. The bankroll is easily replaceable, and could go up to 4K, if needed.

I play mostly $5 minimum, 6deck, pen is around 5 decks, H17, DAS, standard rules. No surrender. My max bet is $100, and I leave at -2 counts and worse. From what I got out of CVCX, it seemed that a bankroll of $3K would be sufficient to achieve this, but my standard deviation was around -130 to 170 units. Is there a way to get the standard deviation to where my expected results would be more positive?

Thanks

[Don Schlesinger]

Standard deviation is, of course, a function of the number of hours that you play. If you spread 1-20, then your hourly s.d. is going to be easily 15 to 20 times your hourly s.d., and there is nothing you can do about that.

You don't say how many total hours your trip will last, but, obviously, for a relatively short one, the trip s.d. will always dwarf the trip s.d. Remember that e.v. is linear: you multiply hourly e.v. by the number of hours played. S.d. is a square-root function: you multiply hourly s.d. by the square root of the number of hours played. If the trip lasts 16 hours, trip e.v. will be 16 times the hourly e.v. and trip s.d. will be four times the hourly s.d.

So, if your e.v. were two units per hour, and your s.d. were 40 units, for the 16-hour trip, the e.v. will be 32 units, while the s.d. will be 160 units, or five times your expectation, and there isn't a thing in the world you can do about it.

Don

[Kirk]

Thank you Don, how do you go about calculating how much bankroll to take with you? So, on a given weekend, I might play 12 hours, spreading 5-100.

Thanks

Standard deviation is, of course, a function of the
> number of hours that you play. If you spread 1-20,
> then your hourly s.d. is going to be easily 15 to 20
> times your hourly s.d., and there is nothing you can
> do about that.

> You don't say how many total hours your trip will
> last, but, obviously, for a relatively short one, the
> trip s.d. will always dwarf the trip s.d. Remember
> that e.v. is linear: you multiply hourly e.v. by the
> number of hours played. S.d. is a square-root
> function: you multiply hourly s.d. by the square root
> of the number of hours played. If the trip lasts 16
> hours, trip e.v. will be 16 times the hourly e.v. and
> trip s.d. will be four times the hourly s.d.

> So, if your e.v. were two units per hour, and your
> s.d. were 40 units, for the 16-hour trip, the e.v.
> will be 32 units, while the s.d. will be 160 units, or
> five times your expectation, and there isn't a thing
> in the world you can do about it.

> Don

[Don Schlesinger]

> Thank you Don, how do you go about calculating how
> much bankroll to take with you? So, on a given
> weekend, I might play 12 hours, spreading 5-100.

Use the calculator here: www.qfit.com/blackjack-calculator-c3.htm

Enter an arbitrary bank, such as 150 units. Enter the e.v. per hour, in starting units and the s.d. per hour, in units. Enter # of hands you plan to play (1200). The output will be risk of ruin. But, you want the ROR to be 2% and would like to know how much bank you need. So, work the calculator backwards, and keep playing with the bankroll entry until the ROR output is 2%.

Clear?

Don

P.S. I think ROR of 2% for a single trip is much too conservative. Do you really need to NOT lose the entire bank you bring with you on a single trip 49 out of 50 times???

[MJ]

> If you spread 1-20, then your hourly s.d. is going to be > easily 15 to 20 times your hourly s.d.,

I believe you meant to write "15 to 20 times your hourly EV".

> You don't say how many total hours your trip will
> last, but, obviously, for a relatively short one, the
> trip s.d. will always dwarf the trip s.d.

Same mistake. You inadvertently wrote s.d. in place of EV for the last word of the sentence. Everything else appears correct.

Regards,
MJ

[Don Schlesinger]

Yes, you're right. Sorry for the carelessness. Not like me.

Don