The effect of Match play on basic strategy

Let’s say I’m playing blackjack, my bet is $25 and a $25 ‘one bet only” match play promo chip. The rule that interests me is this: If I want to double or split, I may do so but only for $25, I can’t double for the promo chip value as well. Does this rule change the correct strategy in some situations? If it’s normally marginally profitable to double, perhaps the fact that I cannot continue to hit if I receive a bad card after doubling means that I’m better off hitting an 11 vs 10 since the double only increases the payout by 50%. Any thoughts?

Most casinos will let you double for the full amount of your bet, so that does suck, but, remember basic strategy doubles down when it's the best mathematical play (advantageous situations for the player). Basic strategy calls for double downs when the player is at an advantage and should put more money on the table, thus you should still in fact put more money on the table. You can think of it as doubling for less, or that your promotion chip isn't part of your regular bet.

Another simpler way to put it: would you double down if you didn't have the promotional chip? Then you should double down with it as well, even if you can't double for the amount of the promotional chip.

Thanks Romes, but I think I’m making a slightly more subtle point. When you double down you lose the ability to continue hitting which means you will win less often. If you double your 11 and draw an ace you are forced to stand on your 12 vs 10. At some point, the potential to win a bit more by “doubling for less” has to be less valuable than the ability to continue hitting. If you had a $10k bet and only $5 more in chips, “doubling” your 11 for $5 against a 10 has to be worse than just hitting, right?

I don’t know what the correct answer is in the match play example but I faced that situation last night with an 11 vs 10. I ended up doubling it anyway but just curious if it was the correct move.

Obviously in a situation like 11 vs 6 it doesn’t matter, you are only taking one more card regardless.

Btw I enjoyed your interview some time back on GWAE.

Even though it is 6am for me and I'm quite tired, I do understand your point (a very fine question actually). The ability to continue hitting or not is taken in to account with basic strategy. You, of course, will lose "a little" to not double on the full amount, but I still believe the correct play is to double what you can, in every situation. The only situation that might be worth discussing is as you correctly identified, 11v10. Here are the Stand, Hit, and Double expected returns via the Wizards Blackjack Appendix (6D H17):

Dealer - Player - Stand - Hit - Double
10 6,5 -0.541929 0.118582 0.178451
10 7,4 -0.538420 0.117891 0.178371
10 8,3 -0.539132 0.117850 0.176919
10 9,2 -0.539813 0.117046 0.173923

The player can expect just under 18% positive return from doubling, and a little under a 12% return from just hitting. Intuitively, doubling is therefor worth about 6% to the player. If you can only double for half the amount, I imagine it would only get you about half the return. YES, it might not be exactly half, but I'd be willing to wager that it would be quite close... thus still worth another ~3% putting the overall return of doubling (for half in this specific case) to about 15% return, still higher.

Again, the overall idea is that the situation is so great for the player, you really want to get as much on the table as you are allowed. There will probably be some break-even point where drawing a card isn't worth the .1% return, but that to my very tired brain is much farther down the line than doubling for 1/2... More like doubling for 1/10th perhaps... and again, that's only for 11v10, the other situations are even more advantageous.

I think you are right, it’s not as close as I thought it was. Thanks, that’s great info.

As I think about your response, it might be even more clear cut. You estimated I would lose half of the delta between hitting and doubling by “doubling for half”, perhaps I only lose 1/4 since my final bet is 3/4 of what the basic strategy assumes.

Perhaps it’s even more complicated because in reality the promo chip is worth ~$12 so I’m betting ~$37 to win $50.... LOL....

Quote: Romes

Even though it is 6am for me and I'm quite tired, I do understand your point (a very fine question actually). The ability to continue hitting or not is taken in to account with basic strategy. You, of course, will lose "a little" to not double on the full amount, but I still believe the correct play is to double what you can, in every situation. The only situation that might be worth discussing is as you correctly identified, 11v10. Here are the Stand, Hit, and Double expected returns via the Wizards Blackjack Appendix (6D H17):

Dealer - Player - Stand - Hit - Double
10 6,5 -0.541929 0.118582 0.178451
10 7,4 -0.538420 0.117891 0.178371
10 8,3 -0.539132 0.117850 0.176919
10 9,2 -0.539813 0.117046 0.173923

The player can expect just under 18% positive return from doubling, and a little under a 12% return from just hitting. Intuitively, doubling is therefor worth about 6% to the player. If you can only double for half the amount, I imagine it would only get you about half the return. YES, it might not be exactly half, but I'd be willing to wager that it would be quite close... thus still worth another ~3% putting the overall return of doubling (for half in this specific case) to about 15% return, still higher.

Again, the overall idea is that the situation is so great for the player, you really want to get as much on the table as you are allowed. There will probably be some break-even point where drawing a card isn't worth the .1% return, but that to my very tired brain is much farther down the line than doubling for 1/2... More like doubling for 1/10th perhaps... and again, that's only for 11v10, the other situations are even more advantageous.

But those double return percentages are based on twice the bet. Imagine that you didn't double, but just took one card in this situation. Those returns would be halved, right? Around 9%? So, while doubling for half may still be the best play here, at some point, as you decrease the amount of your double (E.g., what if you doubled for less for $1 on your $25 bet?), it will be more advantageous to hit rather than double.

I was thinking more about hands like A2 vs. 5 as being a marginal doubling hand that you might want to just hit rather than double for half.

It's only $25, but if you want to eke the last cent of EV, best not to use it on blackjack. See here:
http://www.blackjackforumonline.com/content/beyondcouponsbjfo.pdf

Yes, that’s a fantastic article. But sometimes, especially now, you can’t get a seat at your desired game and life is better if you just play it on BJ rather than waiting around for a seat you may or may not get.

Valid point.