Double Down on Soft 19 and 20

In the instance of having a A/8 in a 6 deck shoe (S17) the win
probabilities are:

52.1 against a dealers 2, 53.7 against a 3, 55.1 against a 4, 56.7
against a 5, 58.6 against a 6, 54.3 against a 7, 50.5 against an 8.

The loss rate is 40.0, 38.6, 37.4, 36.1, 34.5, 38.3, 40.8 respectively.

It's even better for A/9:

Win rate for 2-8 for the dealer is, 55.1, 56.4, 57.8, 59.4, 60.9,
55.9, 53.3 repectively.

With a loss rate of 37.0, 36.0, 34.8, 33.6, 32.3, 36.6, 38.4 respectively.

If the math is correct, why not double down as you would on hard
10's and 11's?

Isn't the objective to press the advantage and get more money out there?

Win rate for 2-8 for the dealer is, 55.1, 56.4, 57.8, 59.4, 60.9,
55.9, 53.3 repectively. Should have read:

Win rate for 2-8 against the dealer is, 55.1, 56.4, 57.8, 59.4, 60.9,
55.9, 53.3 repectively.

Hard 10 and 11 are not "winning" hands and need improvement to become winners.

By winning I mean that since the average dealer hand is slightly over 18 then soft 19 & 20 are inherently winning hands. There is a risk that we may make our winning hand a losing hand by taking another card and lose both our initial bet and the double. Therefore, we stand on soft 19 & 20.

Hard 10 & 11 are not inherently winning hands and need improvement to become winning hands. Since it is more profitable to double than hit these hands, we double them.

Yes, the objective is to press the advantage and get more money out there but only when it is more profitable to do so. Since there is a risk involved with doubling soft 19 & 20, it is more profitable to stay than to double.

HockeXpert

If you meant your post to be an information it's simply wrong. By the way we don't express the value of a hand the way you did and your figures are anyway incorrect. We rather talk of expected value expressed as the percentage of the bet that we statistically win or lose. In the case of A,8 or A,9 (you might as well say 19 or 20) against 2 through 8 , the ev ranges roughly between +40% and 60% and for A,8 and between 65% and 80% for A,9.
The reason why we don't double is simply that we might spoil our total by taking another card.Only with A,8 against 5 or 6 where the dealer bust rate is rather high, the play comes into consideration but even here it's better to stand in a neutral deck.So you better forget about the whole idea.

Francis Salmon

HockeXpert:

The game of Blackjack is not an emotional proposition, but is steeped in math and probabilities. The Math clearly shows an advantage to the player to Double on both Soft 19 and 20 against the dealers up card of 2-8.

Your conclusion is the same as taking insurance on a natural 21 when the dealer is showing an Ace and give up that advantage.

Sure there will be times when the double down will result in a loss of a potential sure hand, or push....there are also chances that the dealer will beat the soft 19/20.

Blackjack is also a game of risk/reward. Let's assume that someone is not counting and is playing basic strategy that typically results in a house advantage of .50, wouldn't the benefit of pressing the advantage of doubling down of soft 19/20's would actually create a positive outcome for the player or close to one?

I plan on doubling down on my soft 19/20's in the future based on the math.

Francis:

The advantage/expected outcome is still the same as Doubling Down on a hard 9 or 10. I get the fact that one is risking taking a winning hand and losing it. But the reward is that one is doubling their bet on a hand that will win more than it loses.

Again, this is not a game of emotion, but rather of taking an advantage whenever it is given.

> The advantage/expected outcome is still the same as Doubling Down on a hard 9 or 10.<

No, there's one less Ace and one less 8 or 9 left in the undealt portion of the deck/shoe -- all values very important when doubling with these totals.

I think there are still tables of EVs for each hand against each upcard over at bjmath.com. I suggest you check your numbers against those tables.

...which leads to the CORRECT data.

The EV's I posted were calculated based on the A/8 and A/9 and take into account the one less A.

I guess there is no dispute that the EV of DD on soft 19/20 against the dealers upcard 2-8 shows an advantage to the player.

If you all want to play safe, by all means, but I plan on exploiting this found advantage, if not only to DD against a dealers 5 or 6 to test the water.

OldCoot:

I still see an advantage in the EV you posted....

"I still see an advantage in the EV you posted."

That isn't the point. No one said that some of the plays you mentioned don't have a positive expectation. But, because a play has a positive edge doesn't mean that you should double. If standing has an even greater edge, the optimal play is the one with the higher e.v., no?

Writing "I still see an advantage" begs the question. Do you not see an even bigger advantage by standing??

Don

well I would never DD on an A8 or A9 a silly thing to do against any card except maybe a 5 or 6 when holding an A8 and a good count

Hi Don:

I will have to look closely at the EV's for Standing vs DD and see where it leads and on which hands do yield better outcomes. I believe that I will see a couple where the play is DD and some to Stand...and much will depend on the rules of the table, how many decks, etc.

It's already known that in a positive deck (or shoe) it can become profitable to double A,8 versus 5 or 6 but for this you need to count cards. All the rest isn't worth considering.

Francis Salmon

After full analysis, I concur that the only advantage is A8 against the dealers 6.

Every little bit helps!!!

No offense to bigjim, but it's kind of funny to watch someone question basic strategy. I mean it's not 1960 when players were using a basic strategy figured by 4 guys at an army base with calculaters. Today's basic strategy is backed up by probably billions of hands of computer simulation. I can appreciate someone questioning it to try to understand better, but there is no need to re-invent the wheel here. It's been done. In the end, they always find as bigjim did that the wheel works best round. lol

kewljason:

First off, I've will never cease to improve my play and will never stop looking for a better mouse trap.

Against a 6 deck shoe, it turns out that there is a slight advantage to dd a A8 against a dealers 6 that is a variance from Basic Strategy.

Moreover, I few other hands may also fall into the mix depending on the count.

Sorry that you got a chuckle out of this and you can stick to playing basic strategy and not question it or look for new possiblities.

I do appreciate each and every response, especially from those who provided valuable insight and information. Thank you OldCootFrom VA for posting the EV tables!

Jim

'Against a 6 deck shoe, it turns out there is a slight advantage to dd A8 vs a dealer that is a variance from basic strategy'

Really? I assume you are talking of the dealer h17, 6 deck game. And for the h17 game basic startegy IS TO DD A8 vs 6! So no there is no variation. Your problem is probably that you are using some sort of 'generic basic strategy' when in fact there are different basic strategies for different sets of rule.

Wow, sorry for wasting your time kewljason. I guess you are the grand swami of BJ. Yes, I'm very aware of many of the various "Basic Strategies", but haven't encountered one that indicated a DD on a A8 against a 6 for 6 Deck H17. Maybe you can enlighten us to it.

Not sure what your attitude is about. No I am not the grand swami of blackjack. But I do play blackjack for a living and damn well know basic strategy. DD A8 vs 6 is basic strategy for most, if not all 6 deck, H17, games. Check the chart on Modern Blackjack, page 54 or the calculator at wizzard of odds, or any of the Qfit product or any reliable book that publishes seperate charts for 6 deck H17 games.