'Session' bankroll ROR

[Qh4Mate]

I recently used the online calculator titled 'Risk of Ruin Given No Goal but a Time Constraint (Trip Ruin)' at https://www.qfit.com/blackjack-calculator-c3.htm to calculate my ROR for a 'Trip':

I used a 400 unit trip bankroll (unit value $5) and a win rate of 2.0 units per 100 hands. I figured a trip to be ten 'sessions' of 150 hands each. Assumption of 75 hands per hour x 2 hrs. = 150. My 'Trip' risk of ruin calculates to:

400 Trip Bankroll units
2.0 Win Rate in units per 100 hands
57 Standard Deviation per 100 hands: 1.14 x SqRt of 100 x $5 (unit value) = 57
1,500 Hands played (10 sessions at 150 hands each for 'Trip')
1.7% Risk of Ruin

(Please confirm that I have calculated the correct Standard Deviation of 57. I got this from BJA 3rd edition page 16.)

My question is: Does it make sense to even calculate a 'Session' ROR? You would just utilize the same calculator but use 40 'Session' bankroll units and only 150 hands? Does the small number of hands render the ROR calculation not really meaningful? I ask this because I get a ROR of 55% per session.
Or maybe ten sessions are too many? Five sessions with 80 units/session drops the ROR to 24%. However, this seems like a small number of sessions for a 'Trip'.

[DSchles]

You can't do the standard deviation your way. First of all, when you spread, rather than flat bet, the s.d. per hand is much larger than 1.14. So you have to simulate to get the correct (larger) value. Second, you're using UNITS for all the inputs. You can't switch to using $5 for the s.d. calculation. That has to be in UNITS as well. So forget the $5.

Use the methodology on page 20, not 16. Don't bother with single session RORs. You can't calculate them properly anyway, until you get the s.d. correct.

Don

[Qh4Mate]

You can't do the standard deviation your way. First of all, when you spread, rather than flat bet, the s.d. per hand is much larger than 1.14. So you have to simulate to get the correct (larger) value. Second, you're using UNITS for all the inputs. You can't switch to using $5 for the s.d. calculation. That has to be in UNITS as well. So forget the $5.

Use the methodology on page 20, not 16. Don't bother with single session RORs. You can't calculate them properly anyway, until you get the s.d. correct.

OK. I looked at the tables on page 20 and read pages 18-21. So now I am convinced this book is way too advanced for me right now. I guess what I need is a beginner's primer on Blackjack Standard Deviation.

[DSchles]

OK. I looked at the tables on page 20 and read pages 18-21. So now I am convinced this book is way too advanced for me right now. I guess what I need is a beginner's primer on Blackjack Standard Deviation.

No you don't, because if you spread your bets, there is no other way to calculate s.d. than the way described on p. 20. So, if you get a beginner's book, it won't help you to answer the question you've asked. Page 16 will be the same as the beginner's book, but I've already told you that you can't answer your question using that methodology.

Einstein once said: Everything should be as simple as possible, but not simpler.

Don

[Qh4Mate]

No you don't, because if you spread your bets, there is no other way to calculate s.d. than the way described on p. 20.

Ok, I am planning to use a bet spread of 1 - 8 units. Looking at the 6 deck game on Table 2.1 (page 20) the "Bet Squared (units)" column indicates a spread of 1 - 6. The bottom formula says "4.70 = one-round s.d. in units". How is this converted to Std. Dev. for 100 hands?
Looking at Table 2.3 (6-deck col) I find the S.D. per round of 4.70. S.D. per hour is 24.32. 26.77 hands played per hour. So I would need about four hours to play 100 hands. Do I take the S.D. per hour and multiply it by four? 24.32 x 4 = 97.28. Is this my S.D. for 100 hands?

[blackjack212019]

Hey,

I'm brand new to this forum. I decided to reply to you because it looks like you know what you're talking about.
I recently did an exercise playing blackjack online.
I played 6,873 hands. of which 3296 were negative, 3033 positive and 544 even.

My question is...
Out of that many hands, do those numbers look proper to you?
The numbers I get (calculating the standard deviation and variance) are not near that
much of a spread from the mean. I'm not great with sd and variance, etc. That is why I'm asking this question.

I did play very close to perfect basic strategy (deviated on some hands like on 15 or 16, etc.

Thanks in advance!
Scott

[Counting_Is_Fun]

Hey,

I'm brand new to this forum. I decided to reply to you because it looks like you know what you're talking about.
I recently did an exercise playing blackjack online.
I played 6,873 hands. of which 3296 were negative, 3033 positive and 544 even.

My question is...
Out of that many hands, do those numbers look proper to you?
The numbers I get (calculating the standard deviation and variance) are not near that
much of a spread from the mean. I'm not great with sd and variance, etc. That is why I'm asking this question.

I did play very close to perfect basic strategy (deviated on some hands like on 15 or 16, etc.

Thanks in advance!
Scott

Yikes lol.

[Gronbog]

I recently did an exercise playing blackjack online.
I played 6,873 hands. of which 3296 were negative, 3033 positive and 544 even.

My question is...
Out of that many hands, do those numbers look proper to you?
Scott

Your results are reasonable. You actually won a few more hands than expected and lost a few less than expected.

In order to calculate the sample variance, you would need the full distribution of the results, including doubles and splits.

[blackjack212019]

Your results are reasonable. You actually won a few more hands than expected and lost a few less than expected.

In order to calculate the sample variance, you would need the full distribution of the results, including doubles and splits.

Thanks for your reply. From those numbers, what would you expect?

[blueman]

Just bring as much cash with you as you can. You never know why you might need it

[Phoebe]

Or simply a credit card.

[Freightman]

Or simply a credit card.

No, no, no. Credit cards have names on them. Possible Exception - a card with a different name than yours, but still under your payment responsibility.

I have such a card printed with my first and middle name only.

[Phoebe]

Isn't a credit card always a withdrawal card at an ATM too ? In France always. And all the casinos that I know have ATMs