"Bad doubles" when backplaying

What would you do when the player you are backplaying makes a bad double? (in my case 11 vs 10 and 9 vs 7, No Hole card)
You cant use appendix 9 directly as you would need a column for "Hit one card only"
If i did it correct EV for doubling 11 vs 10 is about 0,1 (0,177 - 1/13 for Dealer BJ)
Im sure "Hit one card EV" would be lower, so it would be correct to double.

Any thoughts?

Edit: After thinking some more about it, i guess you should always double when the double have positive EV, and in my case adjusted for the probability for dealer BJ.

Most casinos that allow back plays insist that the seated player make all decisions, and the back player must abide by the seated player's actions. Oh, sure, they can discuss it, but the seated player makes the decisions. Discussions will be discouraged if they are lengthy.

However, many casinos do not allow back play, because of the arguments that often ensue.

My advice? Take your lumps, and stop back playing.

Quote: DJTeddyBear

Most casinos that allow back plays insist that the seated player make all decisions, and the back player must abide by the seated player's actions. Oh, sure, they can discuss it, but the seated player makes the decisions. Discussions will be discouraged if they are lengthy.

However, many casinos do not allow back play, because of the arguments that often ensue.

My advice? Take your lumps, and stop back playing.

I played in Vienna, Austria once and nearly every player was playing every square on the table, via back playing. It was incredibly confusing, and the middle-aged German-speaking women HATED it when I would hit a 16 when appropriate. They stopped back playing me pretty quickly :).

It was even more confusing because there were many languages going around at the table.

Quote: DJTeddyBear

Most casinos that allow back plays insist that the seated player make all decisions, and the back player must abide by the seated player's actions. Oh, sure, they can discuss it, but the seated player makes the decisions. Discussions will be discouraged if they are lengthy.

However, many casinos do not allow back play, because of the arguments that often ensue.

My advice? Take your lumps, and stop back playing.

I think the OP's question was if the player in control makes a bad doubling decision, should the back-player raise his/her bet or not. Even though the back-player doesn't have control over playing decisions he/she has the option (in most casinos that allow back-play) of whether or not to place another bet if the controlling player doubles or splits (in the case of a split and a back-player opting not to place another bet, the bet rides on the first split hand).

Oh. I mis-read the original post.

but in that case, do what you want, and if the back player doesn't like it, they can stop playing behind you.

The OP is the back player.

If you aren't allowed to continue to hit as the back player when the seated player doubles, you should still double any +EV situation even though you would rather hit.

If the OP doubles when the double is actually -EV, you should waive your option to double. If you backplay frequently, you'll want to learn the common doubles people make that are actually -EV.

You are correct that Appendix 9 with a no-hole card adjustment is a good way to find these EV

Quote: Kellynbnf

I think the OP's question was if the player in control makes a bad doubling decision, should the back-player raise his/her bet or not. Even though the back-player doesn't have control over playing decisions he/she has the option (in most casinos that allow back-play) of whether or not to place another bet if the controlling player doubles or splits (in the case of a split and a back-player opting not to place another bet, the bet rides on the first split hand).

If this is true, then you would always want to be the back player. As an example, if you have a pair of sixes and the dealer is showing a seven, it is preferable to split, but if you have an option, then only take one hand of 6. One hand of 6 is far better than a hand of 12, and better than 2 hands of 6. If a casino allows such plays, it is just plain stupid. If this is really allowed, then a couple could have one player bet table minimum, and second player back bet the table maximum allowing an advantage play.

Quote: SOOPOO

If a casino allows such plays, it is just plain stupid. If this is really allowed, then a couple could have one player bet table minimum, and second player back bet the table maximum allowing an advantage play.

Casinos allow advantage plays all the time. Just as long as it's not counting.

Quote: P90

Casinos allow advantage plays all the time. Just as long as it's not counting.

In this case I feel like they would catch on pretty quick. Maybe not to the actual play/edge being gained, but just with the bet discrepancy and the strange decisions. Although I've only played one place that even allows back playing...maybe big discrepancies are the norm.

The Wizard does have a page on splitting strategy for back-players:
https://wizardofodds.com/games/blackjack/appendix/19/

According to him (assuming an infinitely small bet from the main player and an infinitely large one from the back-player) about 0.2% could be taken off the house edge using the proper strategy, which basically involves splitting any hand where a single card from the pair is better than the two together; in other words all hands except for 4's (when not split to take advantage of DAS potential), 5's, 9's vs. 7, and 10's. In these cases the back-player would place another bet on any +EV splits and refrain from doing so on the -EV (i.e. "defensive") ones. There is no similar edge gain in the doubling arena since you never double -EV hands (if the hand is in the house's favor you'd just take a hit, even if it's for just one card like a 12 vs. 2 or 3).

I have often played with people back-betting on you.
There is advantage on the Spliting strategy as described above.

BUT, the bigest advantage is to take advantages of the Doubles when other people are back-beting on you and are reluctant to follow on the Double.
You tell them no worries I will Put the Double Bet (make sure that they understand that this is your bet, they are just playing on the initial Bet).
There is a lot of advantage there (depending on the backbettors)

Also for the front Player if he knows that the backbettor will not follow on the double and he can make also the backbettor's double, many more plays that are normally Hit Decisions become Doubel decicions.
For example 9 v 2 (6 decks) Evs are:
Hit: +7.72%
Double: +7.00%
So normally the best EV is Hit.

But, if you can put the backbettor's double (you are efectively tripling the bet) your Ev for Doubling become +10.5%.
So the correct decision is to Double.