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Thread: Aruuba: Analyzing Special Rules

  1. #1
    Aruuba
    Guest

    Aruuba: Analyzing Special Rules

    Just wondered how any of you would go about analyzing the player gain if all 2-card player totals of 20 that resulted in a loss against a dealer 21 total (BJ's & 3-or-more-card 21 totals), were to be treated as a win instead of a loss.
    Same question if it was only a 2-card player 20 vs a dealer BJ.
    Assume a 6-deck, H17, DA2, DAS, no peek game if it matters.
    My inclination was to bet table max, at least in the former case.

    Would some of this sim software out there be able to analyze goofy promo rules like this?

    Thanks for any input.

    I hope it's OK to ask this here.

  2. #2
    Norm Wattenberger
    Guest

    Norm Wattenberger: Is this a real rule somewhere? *NM*


  3. #3
    Coug Fan
    Guest

    Coug Fan: Seems like a pretty straight forward calc

    Unless i'm missing something (very possible), you would just multiple the probability of occurence by 2 (since this would be a 2 unit swing). The probability of a 2 card 20 is around 9.5%, and the probability of a dealer BJ is about 4.8%, so the second case would be (9.5% X 4.8% X 2), or .9% advantage. This is just an approximate calc since I ignored A,9 and did not bother with the effect of removal between player and dealer hands, but you only asked for the process, not the answer, and this is the process that I would follow.

    Actually, now that I read your post again, I see that you said all 2 card player totals of twenty. If this includes split hands, then you would probably want to be a bit more aggressive with ten splitting and this would also impact the calculation of your advantage.

    > Just wondered how any of you would go about
    > analyzing the player gain if all 2-card
    > player totals of 20 that resulted in a loss
    > against a dealer 21 total (BJ's &
    > 3-or-more-card 21 totals), were to be
    > treated as a win instead of a loss.
    > Same question if it was only a 2-card player
    > 20 vs a dealer BJ.
    > Assume a 6-deck, H17, DA2, DAS, no peek game
    > if it matters.
    > My inclination was to bet table max, at
    > least in the former case.

    > Would some of this sim software out there be
    > able to analyze goofy promo rules like this?

    > Thanks for any input.

    > I hope it's OK to ask this here.

  4. #4
    Dreamer
    Guest

    Dreamer: Re: Analyzing Special Rules

    With 6D H17 the dealer will make a BJ or a 3 card 21 on average 8.16% of the time.
    You will make a 2 card 20 (I am guessing including A/9) 10.05% or 9.46% if A/9 is not included.
    Meaning roughly once every 116 hands this will happen.
    I will let you finish the math what a 2 unit swing every 116 hands will do to the BS house edge.

    D.

    > Just wondered how any of you would go about
    > analyzing the player gain if all 2-card
    > player totals of 20 that resulted in a loss
    > against a dealer 21 total (BJ's &
    > 3-or-more-card 21 totals), were to be
    > treated as a win instead of a loss.
    > Same question if it was only a 2-card player
    > 20 vs a dealer BJ.
    > Assume a 6-deck, H17, DA2, DAS, no peek game
    > if it matters.
    > My inclination was to bet table max, at
    > least in the former case.

    > Would some of this sim software out there be
    > able to analyze goofy promo rules like this?

    > Thanks for any input.

    > I hope it's OK to ask this here.

  5. #5
    Dreamer
    Guest

    Dreamer: 10 splitting

    Interestingly the dealer will make far more 21`s with 2-6 showing than with 7-10 showing.
    If holding a 20 you would rather the dealer had a 7 or 8 up than a 5 or 6.
    The 8 bing the best EV card vs 20.

    D.

    > Unless i'm missing something (very
    > possible), you would just multiple the
    > probability of occurence by 2 (since this
    > would be a 2 unit swing). The probability of
    > a 2 card 20 is around 9.5%, and the
    > probability of a dealer BJ is about 4.8%, so
    > the second case would be (9.5% X 4.8% X 2),
    > or .9% advantage. This is just an
    > approximate calc since I ignored A,9 and did
    > not bother with the effect of removal
    > between player and dealer hands, but you
    > only asked for the process, not the answer,
    > and this is the process that I would follow.

    > Actually, now that I read your post again, I
    > see that you said all 2 card player totals
    > of twenty. If this includes split hands,
    > then you would probably want to be a bit
    > more aggressive with ten splitting and this
    > would also impact the calculation of your
    > advantage.

  6. #6
    Aruuba
    Guest

    Aruuba: Re: Is this a real rule somewhere?

    Norm - This was an on-line one week promotion by an RTG casino. It seemed to me they didn't know what they were doing and are probably lucky to still be in business the following Monday morning. Unfortunately, I missed it but want to be ready for it should they repeat it.

    Coug Fan - thanks for your input. I should have said initial 2-card 20's for the player. My mistake. And thank you for showing the process. It's more or less what I was doing too except I think I was forgetting to multiply by 2. This is probably dumb but, given your calcs, are you saying I could just add that 0.9% you mentioned to the HA? In other words, if the HA was 0.5% normally, it would now be a Player edge of 0.4%?

    Dreamer - thanks for your input. For some reason, I thought a dealer might get a 3-card or more 21 total 12% of the time. Maybe that's in single-deck. Maybe that's only when the dealer plays out his hand because he doesn't when the player busts. Where did you go to get your 8.16%? No matter - that's the way I approached the problem, whatever the numbers are.

    It sounds like the first rule is giving a huge player edge of around 2% or more. Is that what you all think? And, against BJ only, would still be a player edge. Is that the conclusion?

    Sounds like betting table max would be proper strategy in either case.

    My related question was where does one go to find out the probabilities of all initial and/or final player hands versus initial and final dealer totals under various sets of rules? Norm - would your CV Data do this? I'm a long-time fan of your CVBJ, btw, and don't know where I would be without it. Poorer, I guess.

    Maybe when my copy of BJA3 arrives, it'll be in there!

  7. #7
    Coug Fan
    Guest

    Coug Fan: Are you sure about the dealer 21 stat

    > With 6D H17 the dealer will make a BJ or a 3
    > card 21 on average 8.16% of the time.

    I apologize for not just looking it up, but on the surface, this seems like a very high rate of 3 card dealer 21's. If we assume that a dealer will get a BJ once every 21 hands, or 4.8% of the time, then you are saying that a dealer will get a 3 card 21 about 3.4% of the time, or about once every 29 hands. This seems high, but you are probably correct. No wonder the dealer always seems to be hitting to 21 on me when I have a 20

  8. #8
    Aruuba
    Guest

    Aruuba: Re: Are you sure about the dealer 21 stat

    > I apologize for not just looking it up, but
    > on the surface, this seems like a very high
    > rate of 3 card dealer 21's. If we assume
    > that a dealer will get a BJ once every 21
    > hands, or 4.8% of the time, then you are
    > saying that a dealer will get a 3 card 21
    > about 3.4% of the time, or about once every
    > 29 hands. This seems high, but you are
    > probably correct. No wonder the dealer
    > always seems to be hitting to 21 on me when
    > I have a 20

    Thanks for your reply - I think I may have had it wrong before.

    I found a table in "World's Greatest Blackjack book" on page 161 that says a dealer will get a 3+ card 21 7.36 % of the time. This plus the 4.83% BJ's mean the dealer gets a 21 12.19% of the time. Hope this helps. (I think this is for single-deck though).

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