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Thread: Hole Carding - Win Insurance Percentage in CVData

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    Hole Carding - Win Insurance Percentage in CVData

    I have some trouble in understanding the exact meaning of this parameter:

    Win Insurance Percentage –
    When you can see the hole card you can’t lose an Insurance bet. You are in control of the number of bets won. But, if you win every bet you will be very obvious. Set this to the percentage of times that the dealer has an Ace up and you see the Ten in the hole that you feel is reasonable to win.

    Let's assume I chose 100 percent percentage of Hole Card seen, so I know the hole card every time.
    The question now is how to deal with the insurance bet. For perfect play and in order to maximize EV,
    I could make perfect Insurance decisions, that means that everytime the dealer has an Ace up:

    - if the hole card is a 10, J, Q, K, I take insurance
    - if the hole card is 2 to 9, I deny insurance.

    To simulate this, I must set the Win Insurance Percentage to 100, n'est-ce pas?
    Now, since this would look too suspicious, I should choose another Insurance behaviour.
    One logical option to me is to never take Insurance, like in Basic Strategy.
    But what Win Insurance Percentage must I enter into CVData in this case?

    If I set this to the default value "0 percent", does this mean that I always make the wrong decision,
    so I take Insurance when the dealer upcard is 2 to 9 and I deny Insurance when the dealer upcard is a Ten?

    Never taking Insurance means that I take the wrong decision in 4/13 = 30 percent of the cases
    and I take the right decision in 9/13 = 70 percent of the cases, so should I set the parameter to 70?

    Or does the parameter mean the percentage of correct bets provided that I choose to take Insurance,
    so I should set the parameter to 0 percent since I don't take Insurance at all?
    I'm somewhat confused about this.
    Last edited by PinkChip; 12-19-2021 at 04:46 PM.

  2. #2
    Random number herder Norm's Avatar
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    Yes, setting it to zero means you will always make the incorrect decision. But, this is an interesting question and I may change how this works.
    "I don't think outside the box; I think of what I can do with the box." - Henri Matisse

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    Maybe the software needs a way to really define an Insurance strategy for hole carding, not just saying how accurate this strategy is.
    To me it seems that if an arbitrary Insurance strategy could be defined before running the sim, the sim itself would have to determine the Insurance success rate (rather than assuming a pre-defined success rate). Certainly the definition would not be as obvious and straight-forward as in card counting, where a count threshold is used. Two possible options would be "Never take insurance" and "Always take Insurance".
    Last edited by PinkChip; 12-19-2021 at 06:27 PM.

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    I don't have this program and don't know if this is an option on it, but in the real world, you can "insure for less" in certain situations. Example being you have a $100 bet and have 20 vs A up with a 7 in the hole. You know you have a guaranteed winner but could toss out a small insurance bet of say $20 to make you look like most civilians. Not something you'd do every time and you can mix it up a bit as not to be too predictable.

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    Yes, that sounds reasonable, and opens up more possibilities for an insurance strategy. I have not yet investigated different strategies for high and low dealer upcards (as supported by the software) but am going to do so. This Cover stuff seems the most special and tricky aspect of hc-ing.

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    Quote Originally Posted by Norm View Post
    Yes, setting it to zero means you will always make the incorrect decision. But, this is an interesting question and I may change how this works.
    The question still remains how to set the Win Insurance Percentage value to simulate the simplest method: Never take insurance (like in Basic Strategy).
    Initially, I made the false assumption that it is 9/13 = 69 %. But in the meantime, I made the following calculation:
    Let us assume the simple case that I don't count, just flat bet and see every hole card (setting the hole card seen percentage to 100).

    Regardless of the other playing strategy, the additional expected value from insurance betting can then be computed independently.

    Win Insurance Percentage = 100%:
    If I always make the correct insurance decision due to my hole card knowledge, the insurance result is 1/13 * 4/13 * (+1 unit) = +4/169 units = +8/338 units,
    that means this changes +8/338 = +2.3669 % in EV with respect to Basic Strategy (never take insurance).

    Win Insurance Percentage = 0%:
    If I always make the wrong insurance decision due to my hole card knowledge, the insurance result is 1/13 * 9/13 * (-1/2 units) = -4.5/169 units = -9/338 units,
    that means this changes -9/338 = -2.6687 % in EV with respect to Basic Strategy (never take insurance).

    The difference in EV between the best and worst insurance strategy is therefore 17/338 = 5.0296 %.
    Since the Never Take Insurance EV is 8/338 lower than the best EV and 9/338 greater than the worst EV,
    I assumed that I have to set the Win Insurance Percentage to 9/17 = 53 %, not 9/13 = 69 %.

    This is very well supported by the sim results I received. I simulated the hole card strategy contained in the QFit folder,
    assuming flat betting 100 dollars per hand, 400 million rounds. Here are the results:

    Win Insurance Percentage: 0 % IBA (Inital Bet Advantage): 5.643 %
    Win Insurance Percentage: 53 % IBA (Inital Bet Advantage): 8.300 %
    Win Insurance Percentage: 100 % IBA (Inital Bet Advantage): 10.668 %

    (see attached screenshots).

    CVDataSimResultsHoleCardingQFitInsurancePercent0.jpg
    CVDataSimResultsHoleCardingQFitInsurancePercent53.jpg
    CVDataSimResultsHoleCardingQFitInsurancePercent100.jpg

    The IBA difference between 0% and 100% Win Insurance Percentage is 5.025%, which is very close to 5.0296%.
    If I set the Win Insurance Percentage to 53%, I get an IBA of 8.300%, which is 2.657% better than the worst case (first row)
    and 2.368% lower than the best case (last row), which is almost exactly the difference in EV computed above.

    So it seems that the default value for the Win Insurance Percentage should be rather 53% than 0%,
    since the simplest strategy is to just ignore the Insurance Bet. I would therefore suggest that for ease of use,
    the software should use a checkbox like "Never take insurance", which when activated greys out the Win Insurance Percentage
    (and automatically sets it to 53 percent for the computations. But isn't the Win Insurance Percentage dertermined by the simulation anyway?
    I could imagine more complex scenarios, e.g. no flat betting, where it has to be determined by simulation a posteriori and cannot be set a priori? Hmm...).
    Last edited by PinkChip; 12-24-2021 at 02:52 PM.

  7. #7
    Random number herder Norm's Avatar
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    Nice SCOREs. Sorry, I'm still working on migrating to a new PC and don't have much time to examine such questions. I will say that much of this should take into account how often you know the HC. If you are lucky enough to have a very sloppy dealer, simply play like a ploppy on insurance -- insure all blackjacks and noting else. If you only occasionally see the HC, play as you would normally according to the count. Players who see the HC normally don't bother to count. Clearly, I need to add some more options. And clearly taking insurance incorrectly is bad. But, you must fail to take it correctly as it remains a sign of an AP. The method currently used should provide the correct EV for a full out hole carder. That's to whom the software is aimed.

    It really comes down to the fact that if you know the hole card, you know if you will win or lose. So, how often do you think you should get away using this knowledge without being tossed? It's a personal decision based upon your experience with a specific casino and the value of that situation.
    Last edited by Norm; 12-23-2021 at 06:10 PM.
    "I don't think outside the box; I think of what I can do with the box." - Henri Matisse

  8. #8


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    Yes, the SCOREs are astronomically high, since not only the EV is so much higher than when card counting but also the variance is much less (also due to the flat betting). I assume that the percentage of dealer hole card seen plays the most important role, similar to penetration when card counting. And insurance performance also has quite an important influence on the resulting EV. I will put the insurance issue aside now and try to better understand what cover plays are useful based upon high and low dealer upcards, in order to try out different strategies for these.

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