Clarification on double downs

[tfg]

So the strategy says to double down in certain situations, lets say an 11 vs whatever. The one question I was thinking about is, lets say that you knew somehow that the next card is something shitty like a 5. Do you still double? Are you playing the double from the getting a 9 or 10 perspective, or is this a long run move? Because lets say the dealer had a 3 up and that you doubled and got the 16, but the dealer breaks anyway. Or would this be a situation where if you knew you were getting a smaller card, you only do it against the dealer bust cards?

I guess another way of asking it is, are you increasing your disadvantage by not doubling every time the situation calls for it?

 

[1357111317]

If you saw the next card and It was a 5 you would never ever double unless you had A,2 A,3 A,4 or A,5. Since there isn't a dealer card that busts more than 50% of the time, ( I think 6 busts 43% of the time) your doubles are banking on the fact that you have a chance of making a hand that will beat the dealer if they make a hand.

 

[tfg]

If you saw the next card and It was a 5 you would never ever double unless you had A,2 A,3 A,4 or A,5. Since there isn't a dealer card that busts more than 50% of the time, ( I think 6 busts 43% of the time) your doubles are banking on the fact that you have a chance of making a hand that will beat the dealer if they make a hand.

Good point.

 

[creeping panther]

Tfg

So the strategy says to double down in certain situations, lets say an 11 vs whatever. The one question I was thinking about is, lets say that you knew somehow that the next card is something shitty like a 5. Do you still double? Are you playing the double from the getting a 9 or 10 perspective, or is this a long run move? Because lets say the dealer had a 3 up and that you doubled and got the 16, but the dealer breaks anyway. Or would this be a situation where if you knew you were getting a smaller card, you only do it against the dealer bust cards?

I guess another way of asking it is, are you increasing your disadvantage by not doubling every time the situation calls for it?

TFG,

You use all info at hand, you never play as a robot, you play as a "BJ Killing Machine".:yikes: The remaining composition of the deck rules all actions, splits, doubles, stand, surrender, hit, or if you play at all.

CP

 

[tfg]

Yeah, playing as a robot is what I've been doing, up until just recently.

 

[sagefr0g]

So the strategy says to double down in certain situations, lets say an 11 vs whatever. The one question I was thinking about is, lets say that you knew somehow that the next card is something shitty like a 5. Do you still double? Are you playing the double from the getting a 9 or 10 perspective, or is this a long run move? Because lets say the dealer had a 3 up and that you doubled and got the 16, but the dealer breaks anyway. Or would this be a situation where if you knew you were getting a smaller card, you only do it against the dealer bust cards?

I guess another way of asking it is, are you increasing your disadvantage by not doubling every time the situation calls for it?

one thing on this tfg, i mean you say 'knowing' what card your going to receive on a double down. really more i think you might suspect it's likely you might get a certain type of card. it's this sort of situation where index plays come into play. example would be illustrious 18 index plays, but there are loads of index plays for which at a given count you may or may not go for a double down. lots of other basic strategy play deviations as well. just not sure if your aware of that or not.

 

[bjsim]

Not Doubling Down

Since you do not know the next dealer card, Not doubling down when needed will cost you. Here are some simulations based on this site Ken Smith basic strategy. You can see the advantage of double down. This simulations are based on 3 million hands .Scroll down to the Double Stat

(Dead link: http://www.bjsim.com/sample/BSKSN2MD1.htm)
(Dead link: http://www.bjsim.com/sample/BSKSN3MD1.htm)
(Dead link: http://www.bjsim.com/sample/BSKSN4MD1.htm)
(Dead link: http://www.bjsim.com/sample/BSKSN5MD1.htm)

 

[rukus]

So the strategy says to double down in certain situations, lets say an 11 vs whatever. The one question I was thinking about is, lets say that you knew somehow that the next card is something shitty like a 5. Do you still double? Are you playing the double from the getting a 9 or 10 perspective, or is this a long run move? Because lets say the dealer had a 3 up and that you doubled and got the 16, but the dealer breaks anyway. Or would this be a situation where if you knew you were getting a smaller card, you only do it against the dealer bust cards?

I guess another way of asking it is, are you increasing your disadvantage by not doubling every time the situation calls for it?

no you would not double 11 v 9 or 10 if you knew the next card was a 5. essentially you would force yourself to stand on a 16 v 9 or 10 with twice as much money down. as soon as you have extra information beyond that assumed by BS and/or counting (ie beyond the count and indices), the optimal strategy changes.

so in your example, you would only want to double if the new total would put you in a +EV situation (ie greater than 50% chance of winning that hand, given the dealer upcard). a 11 + 5 = 16 v a 9 or 10 is not + EV.

 

[KOLAN]

i play
if 4> big card is come out before yours decion, no duble 9,10,11, vs 2,3 7,8,9,10,A

 

[james2009]

Hi TFG,

As far as I know all of the Double Down charts for say multi-deck basic strategy are written when the shoe is exactly zero in High/Low or another way to say this all cards are in the shoe and sims are written based on the first hand only. If someone needs to correct this please do so, but this is my understanding and how I would write such a sim. I say only play when the True Count is positive generally speaking. This method of play creates the most ideal situations for Double Down plays. I remember vividly watching a table after I had dropped out on, some guy at first base betting 500-1000 per hand. He ran into his hard 11 vs dealer 5 at a RC of about -21 with 3 decks left so the TC was about -7. To him it looked like a dream come true but I had a feeling he was going to get beat after his double, and he did. He pulled a low card and the dealer did what I term "hand building" with say 4 low cards. But of course he still could have won. If you only play when the shoe is ten-rich I believe you have a better chance to win these DD hands as opposed to say when the count is negative.

 

[rukus]

Hi TFG,

As far as I know all of the Double Down charts for say multi-deck basic strategy are written when the shoe is exactly zero in High/Low or another way to say this all cards are in the shoe and sims are written based on the first hand only. If someone needs to correct this please do so, but this is my understanding and how I would write such a sim. I say only play when the True Count is positive generally speaking. This method of play creates the most ideal situations for Double Down plays. I remember vividly watching a table after I had dropped out on, some guy at first base betting 500-1000 per hand. He ran into his hard 11 vs dealer 5 at a RC of about -21 with 3 decks left so the TC was about -7. To him it looked like a dream come true but I had a feeling he was going to get beat after his double, and he did. He pulled a low card and the dealer did what I term "hand building" with say 4 low cards. But of course he still could have won. If you only play when the shoe is ten-rich I believe you have a better chance to win these DD hands as opposed to say when the count is negative.

you are correct about BS - it is generated off the top of a shoe as the first hand of play. but the TC is not necessarily 0.

but the OP had next-card information, which changes the optimal strategy from BS or from what his indices say to do.

also, though obviously doubles and splits become MORE profitable at positive TCs, your thinking at negative TCs is incorrect. even at negative TCs it is still +EV to double down on most hands of 11 v (just about all dealer up cards), and 10 v (just about all dealer upcards). just for your info, i would still double down on 11 v X or 11 v 9 even at zen TCs around -10 (NOT THAT I would EVER PLAY TCs of -10) since it is still +EV at that point. i dont even have an index for when it is not correct to double 11 v 6 for instance.

anyway, the purpose of that wasnt to chastise you but to show you how, often, many plays seem "incorrect" to us at very high or very low TCs, but believe it or not, they are still the correct play.

 

[sagefr0g]

an good link on this stuff

tfg here is a good link on this sort of stuff:
http://www.blackjackincolor.com/truecount6.htm

 

[itrack]

i play
if 4> big card is come out before yours decion, no duble 9,10,11, vs 2,3 7,8,9,10,A

translation: if more than 4 big cards in a row come out before my turn i dont double a 9, 10, or 11 vs a 2, 3, 7, 8, 9, 10, or A

 

[Martin Gayle]

translation: if more than 4 big cards in a row come out before my turn i dont double a 9, 10, or 11 vs a 2, 3, 7, 8, 9, 10, or A

Good if the index calls for it. Bad if this is just a hunch.

 

[KOLAN]

translation: if more than 4 big cards in a row come out before my turn i dont double a 9, 10, or 11 vs a 2, 3, 7, 8, 9, 10, or A


[/QUOTE
:sleep::whip:good good dictionary

 

[Katweezel]

consec

translation: if more than 4 big cards in a row come out before my turn i dont double a 9, 10, or 11 vs a 2, 3, 7, 8, 9, 10, or A


[/QUOTE
:sleep::whip:good good dictionary

By george, KOLAN might be on to something. Can anyone tell us what is the probability of getting 5 or more 9s or 10s consecutively in a 6-deck or 8-deck shoe?

 

[Martin Gayle]

By george, KOLAN might be on to something. Can anyone tell us what is the probability of getting 5 or more 9s or 10s consecutively in a 6-deck or 8-deck shoe?

C'mon,

In an infinite neutral deck (5/13) to the power of 5 which is around 1%.

But remember, in an infinite neutral deck the chances of recieving a 6th 9 or X after seeing 5 is 38%. If you get that 6th big card, the chances of seeing a 7th is still 38%.

 

[rukus]

C'mon,

In an infinite neutral deck (6/13) to the power of 5 which is around 1%.

But remember, in an infinite neutral deck the chances of recieving a 6th 9 or X after seeing 5 is 46%. If you get that 6th big card, the chances of seeing a 7th is still 46%.

eh, i was bored at work. heres a simple calc for probabilities of being dealt a 9 or X up to 10 times in a row off the top of a 6 deck shoe.

# 9s	# 10s		Total 9's/10's		Total cards in 6 decks
24	96			120			312
			
xxx 9's/10's dealt	9s/10s remaining	Total cards remaining		Probability of getting xxx 9s or 10s in a row
	1			120			312					38.46%
	2			119			311					14.72%
	3			118			310					5.60%
	4			117			309					2.12%
	5			116			308					0.80%
	6			115			307					0.30%
	7			114			306					0.11%
	8			113			305					0.04%
	9			112			304					0.02%
	10			111			303					0.01%

but yeh, as martin gayle said, about 1% :grin: