Indices for DAS vs No DAS

[bjcount]

My local stores all have DAS so I have not used nor have I studied any NDAS indices. After running a slew of index generating sims using my playing strategy, RPC, I noticed an extreme disparity in the indices for DAS vs NDAS.

I then went and reviewed the other playing strategy indices included with CVData. There again the same large spread in indices between DAS and NDAS.

For example 2,2 vs 2
for DAS split TC>= -3
for NDAS split TC>= +7

So now my question, why if it is ok to split at -3 because you can DD
and why then would you need +7 if you can't double down?

It seems to me that this would be a defensive play in either game, but having a 2 vs 2 with No doubling would be a better hand then hitting with a 4 (2+2) vs 2.

This happens on many indices such as 2,2 vs 3, 3,3vs 2, etc.
With 4,4 vs 4,5, or 6 it's only a hit with NDAS and there are indices to split in DAS.

I am sure I read the explanation in my library of BJ books, but I just can't recall where.

BJC

 

[Renzey]

I notice an extreme disparity in the indices for DAS vs NDAS.

For example 2,2 vs 2 w/ RPC:
for DAS split TC>= -3
for NDAS split TC>= +7

If it is ok to split at -3 because you can DD, why would you need +7 if you can't double down? It seems to me that this would be a defensive play in either game.

With 4,4 vs 4,5, or 6 it's only a hit with NDAS and there are indices to split in DAS.

BJC

It's simply that the extra gain from being able to double your action those times that you catch a card which creates a good doubling hand makes splitting a more efficient choice than hitting with some pairs.

Having 4/4 vs. 6 is a perfect example. Why in the world would you want to trade a mediocre total of 8 in for two lousy totals of 4 each? Because if you catch a 5, 6, 7 or Ace on either 4 (and you will 52% of the time), you've got a profitable double down! That added value with DAS makes 4/4 vs. 6 a proper double with a neutral count.

With 2/2 vs. 2, you're playing defensively whether you hit or split. But with DAS, splitting is less negative than hitting (-.083 EV). With NDAS, just hitting is less negative (-.115 EV). Whereas splitting with NDAS would be -.148 EV (all at a neutral count). As the TC rises, some hands become less negative to split even with NDAS. Similar consequences apply with 2/2 vs 3, with 3/3 vs. 2 or 3, and with 6/6 vs. 2.

 

[bjcount]

It's simply that the extra gain from being able to double your action those times that you catch a card which creates a good doubling hand makes splitting a more efficient choice than hitting with some pairs.

Having 4/4 vs. 6 is a perfect example. Why in the world would you want to trade a mediocre total of 8 in for two lousy totals of 4 each? Because if you catch a 5, 6, 7 or Ace on either 4 (and you will 52% of the time), you've got a profitable double down! That added value with DAS makes 4/4 vs. 6 a proper double with a neutral count.

With 2/2 vs. 2, you're playing defensively whether you hit or split. But with DAS, splitting is less negative than hitting (-.083 EV). With NDAS, just hitting is less negative (-.115 EV). Whereas splitting with NDAS would be -.148 EV (all at a neutral count). As the TC rises, some hands become less negative to split even with NDAS. Similar consequences apply with 2/2 vs 3, with 3/3 vs. 2 or 3, and with 6/6 vs. 2.

Renzey, thank you for the explanation.

BJC

 

[Automatic Monkey]

My local stores all have DAS so I have not used nor have I studied any NDAS indices. After running a slew of index generating sims using my playing strategy, RPC, I noticed an extreme disparity in the indices for DAS vs NDAS.

I then went and reviewed the other playing strategy indices included with CVData. There again the same large spread in indices between DAS and NDAS.

For example 2,2 vs 2
for DAS split TC>= -3
for NDAS split TC>= +7

So now my question, why if it is ok to split at -3 because you can DD
and why then would you need +7 if you can't double down?

It seems to me that this would be a defensive play in either game, but having a 2 vs 2 with No doubling would be a better hand then hitting with a 4 (2+2) vs 2.

This happens on many indices such as 2,2 vs 3, 3,3vs 2, etc.
With 4,4 vs 4,5, or 6 it's only a hit with NDAS and there are indices to split in DAS.

I am sure I read the explanation in my library of BJ books, but I just can't recall where.

BJC

To put it all in perspective, yes the split strategy and indices for DAS vs. not are going to be very different. But those indices aren't worth very much. The only split indices with a significant cash value are XX vs. 5 and 6, and obviously those are going to be the same whether or not you can DAS.

 

[Kasi]

This happens on many indices such as 2,2 vs 3, 3,3vs 2, etc....

I don't know bjcount - basically maybe because BS is to basically hit those hands with NDAS and split them with DAS.

So the departure from BS would be to just hit them in DAS at -3 rather than split. And the departure from BS with NDAS would be to split them at +7 rather than hit.

At least that's why one is negative and one is positive while the number means the same thing - "split at that number or more".

Not a good explanation I'm sure lol.

Why are they what they are - because CVDATA said so lol.

Ours is not to reason why
Just apply. lmao.

My rhyming pales in comparison to our resident poetry laureate - The Wise One lol.

 

[Blue Efficacy]

short answer

The ability to double down strengthens your defenses in these defensive splits.

Think about it, you win one doubled hand, that covers the loss for the other half of the split which might have been a stiff. With DAS you can win one half of your split and have a net profit for the round. With no DAS you cannot do that.

 

[bjcount]

The ability to double down strengthens your defenses in these defensive splits.

Think about it, you win one doubled hand, that covers the loss for the other half of the split which might have been a stiff. With DAS you can win one half of your split and have a net profit for the round. With no DAS you cannot do that.

Thanks to all for the replies.

The concept of why we make the appropriate play I understand, but that does not explain (other than Renzey's reply) the huge disparity in the indices from DAS vs NDAS.

If your going to put out more money to make the split, than even in a NDAS game you have the same potential for a push. If it's a defensive play and the chances of improving your hand is 52% than the chances of improving your hand is still the same whether it's DAS or NDAS (at neutral count).

Would it be that in NDAS, say if you have a 3,3 vs 2 and the index to split is +7, you are relying on the dealer to bust since the shoe is heavy in high cards? In the DAS where the index is -3, you are putting out more money in the chances (now is it < or > 52%?) that you will improve your hands and have the chance for a DD. Now your putting more money out in a negative situation. If you do it in a negative situation for DAS, than how much different is NDAS going to be for the same hand?

Renzey's math example probably spells out the answer best.

BJC

 

[FLASH1296]

28%

The Dealer's Bust Probability contributes relatively little to the +7 play.

Off the top the Dealer busts a bit over 28% of the time on average.
With a (Level One) +7 True Count I suspect that the dealer's bust %
will rise to close to 30%

Contrary to our intuitive (but thoroughly incorrect) reasoning,
the Dealer's overall bust % does not move very much in
accordance with a changing True Count.

 

[chichow]

to the OP

It would help to know what kinda of count you are using in order to better answer your questions....

 

[Blue Efficacy]

DAS gives you more potential gain by making the split at neutral counts, that's why the indexes are much lower.

 

[bjcount]

The Dealer's Bust Probability contributes relatively little to the +7 play.

Off the top the Dealer busts a bit over 28% of the time on average.
With a (Level One) +7 True Count I suspect that the dealer's bust %
will rise to close to 30%

Contrary to our intuitive (but thoroughly incorrect) reasoning,
the Dealer's overall bust % does not move very much in
accordance with a changing True Count. [/SIZE][/COLOR]

Flash,
Using RPC (lvl 2) with 1/2DTC a TC +7 is so rare, I bet you if I saw it 4 times (6d) in 500 hrs of play that would be a lot, so I would say the high ten count would cause the dealer to bust much greater than 30% (if she didn't pull 20's throughout the high count).

to the OP

It would help to know what kinda of count you are using in order to better answer your questions....

It's posted in the original post, RPC, level 2.

DAS gives you more potential gain by making the split at neutral counts, that's why the indexes are much lower.

Thanks BE, that agrees with Renzey's math.

BJC

 

[Kasi]

Flash, ...so I would say the high ten count would cause the dealer to bust much greater than 30% ...

Probably because, for the hands in question vs a dealer 2, that is what we are basically talking about?, the dealer bust percentage is like 35-36% at only a neutral count.

To find out what comparing an average dealer bust %age over all dealer upcards has to do with what you are asking, I guess you'd have to ask THE FLASH.

 

[FLASH1296]

Blackjack Dealer Bust Percentages

Dealer 2 3 4 5 6 7 8 9 10 Ace
Bust % 35% 37% 40% 42% 42% 26% 24% 23% 23% 17%


Average dealer bust is 28% at ZERO T.C.

At extreme low counts the dealer's bust % drops, as expected.

The same is not true for extreme high counts.

At typically observed high T. C.'s the dealer's bust % hardly increases at all.

 

[bjcount]

Blackjack Dealer Bust Percentages

Dealer 2 3 4 5 6 7 8 9 10 Ace
Bust % 35% 37% 40% 42% 42% 26% 24% 23% 23% 17%


Average dealer bust is 28% at ZERO T.C.

At extreme low counts the dealer's bust % drops, as expected.

The same is not true for extreme high counts.

At typically observed high T. C.'s the dealer's bust % hardly increases at all.

This doesn't explain why the indices are vastly different, my original question, between DAS and NDAS.

Not being a math guy, I still do not see how in a high count when the dealer has a stiff hand, his % of busting does not increase, for the same reason that high TC's tend to improve your DD results.

The 28% rate is based on a range of TC's, say from -9 to +9 for example only. There must be a way to graph a % curve for dealer busting as the TC goes through it's range as it applies to a specific hand type (say 2,2 vs 2). What your saying is if we chop off all neg., 0, & +1 TC integers, and use the same hand type (2,2 vs 2), the dealers bust rate will still remain the same. Now that just can't be correct.

BJC

 

[FLASH1296]

Clarification:

This will clarify what I am saying.


The probability of the dealer busting does not grow very much as the T.C.

grows, mostly because the dealer gets fewer and fewer stiffs to draw to.

Surely the dealer displaying a stiff card will break more often at high true

counts; BUT the dealer rarely has to draw a card at high plus counts.


Is that more clear now ? I hope so.

 

[bjcount]

This will clarify what I am saying.


The probability of the dealer busting does not grow very much as the T.C.

grows, mostly because the dealer gets fewer and fewer stiffs to draw to.

Surely the dealer displaying a stiff card will break more often at high true

counts; BUT the dealer rarely has to draw a card at high plus counts.


Is that more clear now ? I hope so.

Thanks for trying, but those points I understood. You are still refering back to the "standard" that when the count is high the dealer will draw less stiffs. That does not relate to my question about DAS vs NDAS indices being so extremely far apart.

If we rephrase the "standard" to say that if every time the dealer draws a hand assuming it is always a stiff hand, then the dealer will bust more as the TC rises. So in essence, the bust rate for the SAME hand type will increase as the count rises. The bust rate could not always be constant or with little rise.

Again, Renzey's math explained the answer to my question. The reason that DAS indices are lower than NDAS indices is because the -EV (using 2,2 vs 2 as an example) is higher (less of a loss) when you can DAS in a neutral count than there is NDAS (higher loss).

Now at an index of -3 you split in DAS
but in NDAS you wouldn't split until an index of +7. CVData had developed these optimum indices to provide the best available outcome. It just seems that the range was so wide that if the dealer had a 2 and the count was even +4 his chance of busting was much greater than 28%.

Well just to satisfy myself I ran two sims using my RPC indices for DAS and the same exact indices in NDAS. In a play all game, $10u, DAS had a win rate of $26.71, NDAS had a win rate of $22.45.

Sorry if I lost anyone....

BJC

 

[FLASH1296]

If one uses S.B.A. to generate a wide range of indices there are sometimes produced indices that actually change radically at different points along the True Count spectrum. This includes reversals of going from + to - as well as some that are just linear with "blank spots" so that a B.S. play may be violated only within a particular range and may or may not return to being a sound departure index at a yet higher or lower T.C.

The above was absolutely true about S.B.A. some years ago, and were referenced as "reverse indices"; but I cannot confirm that it is still so.

It is possible that an index in can be + or - (and very divergently so) when DAS or NDAS is taken into consideration. The reason for this is that when DAS is considered it is a one-card play that responds very well to a high density of Face Cards. With NDAS numerous small cards can be beneficial to the player making the play, but more importantly your expectation of the dealer creating a busting hand (often a hand of precisely 22) is less unlikely at +7. The DAS index of -3 means that we ought to consider doubling unless our T.C. is less than (more negative than) -3.

My feeling is that these are not Risk Averse indices. I, myself, do not use an e.v. maximizing matrix myself.

 

[bjcount]

My feeling is that these are not Risk Averse indices. I, myself, do not use an e.v. maximizing matrix myself.

These are RA indices, remember I do not use Zen, nor do I use 1DTC so your indices may be double mine.

BJC

 

[FLASH1296]

An unanswerable question

Lets keep in mind that these 2 indices are far apart and the Basic Strategy plays are different.

B.S. in a DAS game supports a lot of pair-splitting, 2,2 vs. 2 included.
B.S. in a NDAS game. is quite restrictive on pair splits.

2,2 V. 2 is NOT a B.S. pair split in a NDAS game, unless it is Single Deck.

With NDAS hitting the deuces vs. a deuce is 2.66% less costly than splitting.

As far as the "effects of removal"[EoR] are concerned 8's and 9's are the only cards significantly effecting this playing decision.

Indeed, none of the other ranks are of consequence, except for the 5 which has far less than 1/2 the effect of the 8's and 9's.

Traditional Card Counting cannot help us with this decision because the
8's, and most of the time the 9's, and sometimes the 7's are NOT counted.

 

[bj bob]

This doesn't explain why the indices are vastly different, my original question, between DAS and NDAS.

BJC

Let me see if I can clarify this issue for you from a different perspective.
The DAS rules open up another whole "mini game" within the game. As you have mentioned the index differences between DAS and nDAS are quite substantial and the reason is that the index matrices (being much lower) "encourage" more splits in DAS simply because any split with the further possibility of doubling is an advantage to the player. As Fred said the possibility of catching a 7,8,9 etc. on your split are rather good and, as the BS chart indicates in most games a final dd combination of 9, 10 and 11 are in fact a positive advantage at that point of time. Add that to the fact that a split in DAS in not finite as it is in nDAS. In theory you can split and catch dd combinations for quite a while, resulting in multiple favorable and advantageous hands.
In the end, the many chances to catch a dd combination with twice the bucks on the felt per hand become the new "end game" in DAS. Even losing the flat hand but winning double on the other still yields a net gain to the player.