billryan
Joined: Nov 2, 2009
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July 16th, 2021 at 10:50:16 AM permalink
It seems to me that you are thinking that since it is more advantageous to double against a 2-6 than a high card, that you should only double against the low cards.
If so, you are looking at it the wrong way.
Don't compare the results for doubling against a 2-6 vs doubling against a high card. Those results are utterly meaningless to this equation. The only thing that matters is: Is doubling against a high card better or worse than simply hitting.
Not doubling against ten means you lose out on almost a third of your potential doubles and will take an almost break-even game into severely negative territory.
sabre
Joined: Aug 16, 2010
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July 16th, 2021 at 10:51:24 AM permalink
Quote: bcmarshall

Would I win more money overall by ignoring high card doubles?

You don't make more money by making plays that make less money.
Mission146
Joined: May 15, 2012
• Posts: 14626
July 16th, 2021 at 11:13:15 AM permalink
Okay, so here is what we are going to do to illustrate your situation. Apparently, the calculator here:

https://wizardofodds.com/games/blackjack/hand-calculator/

Is not by itself sufficient just looking at that one decision point, so what we are going to do is use the calculator in a different way.

For this, we will look at the case of doubling a Hard total of 11 against a dealer showing ten vs. hitting. Naturally, the dealer peeks for Blackjack, or you would not be doing this. This represents one of your less favorable doubling situations, but is still advantageous.

What we are first going to do is look at the expected values of standing on certain hand totals, 17-21, AFTER Hitting/Doubling 11 as you would be doing that anyway:

Stand on 17: -.421221 or -.842441 (If you had doubled)

Stand on 18: -.180423 or -.360846 (If you had doubled)

Stand on 19: +.062002 or +.124004 (If you had doubled)

Stand on 20: +.554446 or +1.108892 (If you had doubled)

Stand on 21: +.962687 or +1.925374 (If you had doubled)

Let's add these all up:

.962687 + .554446 + .062002 - .180423 - .421221 = 0.977491 (Hitting to total 17-21)

AND:

1.925374 + 1.108892 + .124004 - .360846 - .842441 = 1.954983 (Doubling to Total 17-21)

From this, we learn two important things:

1.) The only results from the hit/double where the player is expected to WIN money are hand totals 19-21, which is going to be true whether you hit or you double.

2.) As an extension of #1 and with eight decks, only hitting/doubling and receiving an eight, nine or ten actually gets you to the point where the hand value against a ten is in your favor. I've started you with 6-5 to keep this somewhat simple. There are 413 remaining cards (the dealer has a ten), so there are (8, 9, 10, J, Q, K) six ranks and (6 * 4 * 8) - 1 = 191 cards that get you to this point. (Six ranks * Four Suits * Eight Decks) - (Dealer has a ten).

Now, by hitting instead of doubling (unless you hit and get a five for sixteen total, in which case, you would still stand) you create additional opportunities to perhaps get to the most desired hand totals of 19-21, which are your ONLY profitable expectation totals. However, the probability of reaching those totals from the various hand totals that would result in continued hitting (12-15) are going to be insufficient to make up the positive value of doubling and getting to those totals with one card.

In fact, the quickest way to any of those totals is with one card. It doesn't matter that you have a greater probability to win a few more hands here and there because that probability is insufficient to compensate for the lost value of not doubling your bet when you had the chance.

And...THAT's against a dealer TEN!!! You're sacrificing WAY more value not doubling against 7-9!
https://wizardofvegas.com/forum/off-topic/gripes/11182-pet-peeves/120/#post815219
bcmarshall
Joined: Jul 11, 2021
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July 16th, 2021 at 11:52:22 AM permalink
Quote: Mission146

I don't know if there is some angle vis-a-vis advantage play that has you playing Blackjack in the first place, but if not, then you're not playing Blackjack to win money. You will not win money, lifetime, playing a game that is negative expectation to begin with. The only thing that you will accomplish, by making the right playing decisions, is to lose your money playing a -EV game more slowly.

That out of the way, yes, you are ONLY doubling when you have the advantage in the hand to begin with. I will illustrate this in my next post with an example because I fear that it is necessary.

Because you have the advantage in the hand in your doubling situations, you will indeed win more money by betting more with this advantage, as appropriate. Please stay tuned for the next post, but I'm going to need a few minutes.

I understand the point you're making. As I said, I'm posing a question, and providing the logic behind my reasoning. In no way am I suggesting this is correct strategy. I just wanted to hear what all of you thought.

Looking forward to your next post.
odiousgambit

Joined: Nov 9, 2009
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July 16th, 2021 at 1:22:34 PM permalink
This is a type of gambler's fallacy encountered a lot at this site. When consulting those places where they list fallacies, this one is hard to find. What name should it have?

The player is losing at a negative expectation game using best strategy, and gets frustrated. He respects the idea that it is best strategy, but somehow feels like it is not serving him well. He keeps losing, maybe has been on a losing streak. Usually, but not in this case, note well I say not in this case, his frustration makes it occur to him that he will lose less money if he hedges his bets. I won't go into what happens with that.

In this case the player wants to avoid betting more money [doubling] when the expectations change only marginally. Why isn't it better to bet less and live longer? The problem with that has multiple angles, but one he doesn't see too easily is that he is lowering the variance. The player's only hope all along has been variance, because he is playing a negative expectation strategy. With greater variance, he might win more sessions. He actually might be better off to consider doubling when BS says not to, if the individual instance has just a slight decrease in expectations, to boost variance*. His thinking process, though, is taking him into the wrong direction.

Does this fallacy have a name?

* I'm not going to say I'm recommending that, exactly
the next time Dame Fortune toys with your heart, your soul and your wallet, raise your glass and praise her thus: “Thanks for nothing, you cold-hearted, evil, damnable, nefarious, low-life, malicious monster from Hell!” She is, after all, stone deaf. ... Arnold Snyder
moses
Joined: Sep 23, 2013
• Posts: 436
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July 16th, 2021 at 2:01:03 PM permalink
11vs10 will occur 1.4%. win 51% lose 42% tie 7%.

100k hands' 1400 doubles. 714 wins. 588 loss. 98 ties.

This is far below 65% win goal in the OP.

Basic Strategy are thresholds. Not advantages.

Again, this is why one counts. The win percentages increases the more positive the deck. Hitting and getting two cards is more likely the more negative the deck.

The humor in basic strategists. They hit 16vs10 and want a 5. They double 11vs10 and want a 10. Yet, have no idea of deck composition.
Last edited by: moses on Jul 16, 2021
FinsRule
Joined: Dec 23, 2009
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July 16th, 2021 at 3:01:43 PM permalink
The math says double, so you double. If you want to play by feel that's fine, but if you're going to play blackjack regularly, you'll just lose more. This is an easy one.
bcmarshall
Joined: Jul 11, 2021
• Posts: 32
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July 16th, 2021 at 3:04:18 PM permalink
Quote: odiousgambit

This is a type of gambler's fallacy encountered a lot at this site. When consulting those places where they list fallacies, this one is hard to find. What name should it have?

The player is losing at a negative expectation game using best strategy, and gets frustrated. He respects the idea that it is best strategy, but somehow feels like it is not serving him well. He keeps losing, maybe has been on a losing streak. Usually, but not in this case, note well I say not in this case, his frustration makes it occur to him that he will lose less money if he hedges his bets. I won't go into what happens with that.

In this case the player wants to avoid betting more money [doubling] when the expectations change only marginally. Why isn't it better to bet less and live longer? The problem with that has multiple angles, but one he doesn't see too easily is that he is lowering the variance. The player's only hope all along has been variance, because he is playing a negative expectation strategy. With greater variance, he might win more sessions. He actually might be better off to consider doubling when BS says not to, if the individual instance has just a slight decrease in expectations, to boost variance*. His thinking process, though, is taking him into the wrong direction.

Does this fallacy have a name?

* I'm not going to say I'm recommending that, exactly

I suppose you could give it my name if you want!

Just kidding, but I see the point you're making. I hope I made the reasoning behind my question clear.

The 58% looks a lot better than the 14%, but the bottom line it appears is that positive is positive.

But let me phrase this a different way. I know that between 60% and 65% of my attempts are converted to wins by only doubling on dealer small cards. If I double as the "Good Book" says and my percentage goes down to say 55%, wouldn't that make a case for my suggestion?
bcmarshall
Joined: Jul 11, 2021
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July 16th, 2021 at 3:04:54 PM permalink
Quote: FinsRule

The math says double, so you double. If you want to play by feel that's fine, but if you're going to play blackjack regularly, you'll just lose more. This is an easy one.

Thanks. I appreciate the logic in that.
FinsRule
Joined: Dec 23, 2009