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Thread: How to bet if you know the possibilities before each hand.

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    How to bet if you know the possibilities before each hand.

    If you know you have a 2.5% possibility for example to win over losing how much should i bet as percentage of the balance?
    Any advice?!

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    Quote Originally Posted by wax View Post
    If you know you have a 2.5% possibility for example to win over losing how much should i bet as percentage of the balance?
    Any advice?!
    I Think not more than 2.5% over minimum bet. The emphasis for me is on "Know". On the other hand if you're Guaranteed, put out the maximum bet. But then it wouldn't be Blackjack.

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    Quote Originally Posted by wax View Post
    If you know you have a 2.5% possibility for example to win over losing how much should i bet as percentage of the balance?
    Any advice?!
    Let me see if I can put this into language that reflects what you're truly asking: "If you know you have a 2.5% greater probability to win a hand, over losing, how much should you bet as a percentage of the bankroll?" Is that what you meant to write? If so:

    In a 4.5/6 S17 DAS game, having a 51.25% probability of winning a hand (ties excluded) and, therefore, a 48.75% probability of losing, represents a 2.5% greater probability of winning over losing. To have those percentages, the true count would be approximately +8, and your edge would be around 4.32%. As the correct Kelly wager is edge divided by variance, and variance is about 1.31, the correct percentage of your bank to bet would be about 3.3%. For many players, that's more than a max bet.

    Don

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    Quote Originally Posted by Jack Daniels View Post
    I Think not more than 2.5% over minimum bet. The emphasis for me is on "Know". On the other hand if you're Guaranteed, put out the maximum bet. But then it wouldn't be Blackjack.
    2.5% advantage with my standard rule set equates to better than +5 TC.

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    Quote Originally Posted by DSchles View Post
    In a 4.5/6 S17 DAS game
    Don - I think it's time to default to H17 as the standard. With the exception of PA and some scattered HL games elsewhere, S17 is dead.

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    Quote Originally Posted by DSchles View Post
    Let me see if I can put this into language that reflects what you're truly asking: "If you know you have a 2.5% greater probability to win a hand, over losing, how much should you bet as a percentage of the bankroll?" Is that what you meant to write? If so:

    In a 4.5/6 S17 DAS game, having a 51.25% probability of winning a hand (ties excluded) and, therefore, a 48.75% probability of losing, represents a 2.5% greater probability of winning over losing. To have those percentages, the true count would be approximately +8, and your edge would be around 4.32%. As the correct Kelly wager is edge divided by variance, and variance is about 1.31, the correct percentage of your bank to bet would be about 3.3%. For many players, that's more than a max bet.

    Don
    Don - thank you for this excellent response and detailed breakdown.
    As a follow up I am curious to know if the variance of 1.31 is specific to this type of game/scenario or blackjack in general with basic strategy and deviations at play. If we add LS to the game outlined would that lower the variance and increase the player's edge?
    If so, wouldn't that correspond to an even higher percentage of bankroll than the 3.3% to almost 4% as the optimal bet? Lastly, where can I learn more about calculating variance for blackjack?
    Last edited by CuriousOne; 05-25-2022 at 08:49 AM.

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    If we add LS to the game outlined would that lower the variance and increase the player's edge?
    yes

    If so, wouldn't that correspond to an even higher percentage of bankroll than the 3.3% to almost 4% as the optimal bet?
    Yes, 2 factors. Surrender adds about a 1/3 to win rate. Don I think is including the value of index play - I18 for example - which increases edge per true count the higher the TC becomes - examples - 8v6, 8v5, 99v7 10v10, 10 10v 5 or 6, insurance etc.

    Point - optimal betting of entire bankroll at that point should provide an excellent view of the exit which will include a guided tour.

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    So, is there a function that correlates bets with the propability avadage?
    Is it linear?
    I guess 8deck, no surrender, with dealer to stop on soft 17 is a good example.

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    Freightman - thanks for your reply. It has led me to the last piece of this puzzle found here Variance in Blackjack (wizardofodds.com) this site confirms your data on the variance of Late Surrender -0.03629 or -3.6%
    And your point is well taken - if your goal is to maximize your money knowing this will be a one and done casino then this is optimal.

    Assuming these variance calculations are correct, combined with previous published player advantage tables (or casino edge) for various games (4.5/6 S17 DAS being -0.428 player advantage at a TC 0)

    We can calculate the optimal bet using: Player Advantage / Variance as a percentage of bankroll, outlined by Don above.

    Note: please let me know if we are permitted to link to other on line sources or not and I will edit post if necessary.
    Last edited by CuriousOne; 05-25-2022 at 02:02 PM.

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    A quick comment on all of the above. The OP wasn't very clear as to exactly what he meant by 2.5% "possibility to win over losing." I know very well, via hundreds of Chapter 10 charts, what the player edge is at every TC for every number of decks and every rules set. But I took the wording literally, namely that the player would win 2.5% more hands than he would lose. Hence my response. If that isn't what the OP meant, then he should come back and clarify.

    Don

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    And your point is well taken - if your goal is to maximize your money knowing this will be a one and done casino then this is optimal.
    Not withstanding execution of some revenue maximizing plays not necessarily leading to a “one and done”, other very interesting points are evident.

    A “standard” approach to question answering is in place. This would include, among other things, optimal spreads and would of course include “best mathematics”. They’re many good reasons to deviate from optimal betting, and those reasons are varied and correlate to the goals of the individual.

    For myself, my approach to revenue maximization has changed significantly over the years - from heavy volume play not being concerned about variance (because of volume) to a more variance averse approach today (because of lack of volume). These comments notwithstanding gains of that type from the regaled FBM ASC.

    The overall general point here is that
    1. There is a mathematical approach that maximizes revenue and should be the standard to question answering
    2. That mathematical approach, robotically applied leads to faster escorted tours to the front door
    3. Deviations of that optimal mathematical position, executed by competent AP’s, lead to increased longevity
    4. For the birthing AP, that individuals goals should be taken into account to fashion a style of play corresponding to those goals.

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    You cannot exclude ties, it's about an 8% probability. So to fill the Kelly equation you have to find more accurately the lose probability.
    But how?

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    Quote Originally Posted by wax View Post
    You cannot exclude ties, it's about an 8% probability. So to fill the Kelly equation you have to find more accurately the lose probability.
    But how?
    You're asking the wrong question. To determine Kelly wagers, you don't need to know anything about how many hands you win, lose, or tie. You need only know what your overall advantage is, at any particular true count. Many wagers in BJ pay more than even money (naturals, splits, doubles), and some losing wagers are less than 100% of your bet (insurance, surrender). So, stop talking about winning and losing probability; it isn't what you're looking for.

    Don

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