Blackjack quiz

Which mistake is the biggest blackjack mistake in terms of EV?


  • Total voters
    48

sagefr0g

Well-Known Member
jack said:
88v7 is most costliest play, but because its so infrequent, my bet is on 12v7 over-all.
hmm, yeah i didn't consider the frequency for which the hand presents.:rolleyes:
 

callipygian

Well-Known Member
sagefr0g said:
hmm, yeah i didn't consider the frequency for which the hand presents.:rolleyes:
Crap, I forgot to take that into account as well. Should've cheated and read the thread first. :p

Taking into account the frequency, Sh12vT might actually be more costly than Sh12v7. Sh16vT is less frequent and probably less costly than Sh12vT, so that's definitely out.

I'd like to revise my answer to Sh12vT - with Sh12v7 a close second, and then H88v7 third and Sh16vT last.

Edit: highlight below for spoiler
Sh12vT: -4.1 mEV, Sh12v7: -1.7 mEV, H88v7: -0.3 mEV, Sh16vT: -0.0 mEV
highlight above for spoiler
 
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Cardcounter

Well-Known Member
When I asked the question I did not take freaquency into account that was not the question. Not Splitting 8,8 vs a 7 costs the player on average 64% of his orginal bet. Not hitting a 12 vs a 7 costs about 25%. Not hitting a 12 vs a 10 costs about 20%. Not hitting a 16 vs a 10 is a marginal play costs on average 3%.
 

bjcount

Well-Known Member
Cardcounter said:
When I asked the question I did not take freaquency into account that was not the question. Not Splitting 8,8 vs a 7 costs the player on average 64% of his orginal bet. Not hitting a 12 vs a 7 costs about 25%. Not hitting a 12 vs a 10 costs about 20%. Not hitting a 16 vs a 10 is a marginal play costs on average 3%.
Here are the 6d,s17 numbers from the ev chart:
Which mistake is the biggest blackjack mistake in terms of EV?
Not hitting 12 vs a 7
(ev= -0.477)
not splitting 8,8 vs a 7 (ev= -0.48)
not hitting 16 vs 10 (ev= -0.536)
not hitting 12 vs a 10 (ev= -0.540)

Playing the hand correctly using BS:

12 vs 7, hit = ev -0.27
8,8 vs 7, split = ev +0.319
16 vs 10, stand= ev -0.54 / hit= ev -0.534
12 vs 10, hit= ev -0.375

than 8,8 vs 7 is clearly the largest mistake we could make.

hand probability:
12vs 7 (t,2 vs 7) 0.003677
8,8 vs 7 0.00044
16 vs 10 (t,6 vs 10) 0.014553
12 vs 10 (t,2 vs 10) 0.014553


based on frequency 12 vs 10 is the overall costliest mistake.
BJC
 
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callipygian

Well-Known Member
bjcount said:
hand probability:
12vs 7 (t,2 vs 7) 0.003677
8,8 vs 7 0.00044
16 vs 10 (t,6 vs 10) 0.014553
12 vs 10 (t,2 vs 10) 0.014553
You're underestimating the player hands.

Hard 12 can be made with T2, 93, 84, 75, as well as 2T, 39, 48, 57. Likewise, hard 16 is T6, 97, 79, 6T. 88 can only be made with 88.
 

bjcount

Well-Known Member
callipygian said:
You're underestimating the player hands.

Hard 12 can be made with T2, 93, 84, 75, as well as 2T, 39, 48, 57. Likewise, hard 16 is T6, 97, 79, 6T. 88 can only be made with 88.
For a sample I used just the 10v2, and did not add in all the other hand types & frequencies of each for a total.

After I posted above I went to look at the hand combo's that make up hard 12. It still worked out the to the same end result that 12 vs 10 was the costliest mistake when you include hand frequency. You'll pull 12 v 10 30x more frequently than 8,8 vs 7.

I wouldn't think to look at the inverse hands in BJ as you would in craps where two dice can roll 3,4 or 4,3, but interesting thought.

Thanks

BJC

Note: the other three hard 12 hand combos add a frequency of 0.0027 for a total of 0.0063 (not including their inverses)
 
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KOLAN

Well-Known Member
12vs 7
because all players know allweis split 88(there not gonna do mistak laik this )
 

callipygian

Well-Known Member
bjcount said:
I wouldn't think to look at the inverse hands in BJ as you would in craps where two dice can roll 3,4 or 4,3, but interesting thought.
You don't need to if you're comparing the relative frequencies of two hard hands, but if you're computing absolute frequencies or if you're comparing relative frequencies of a hard hand and a paired hand, you need to look at the "inverse hands".

People in general (and I am no exception, seeing as I didn't remember when answering the poll!) vastly underestimate the infrequency of paired hands compared to non-paired hands. As you pointed out, hard hands, especially 12's and 13's (which have the most combinations) are dominatingly frequent.
 

aslan

Well-Known Member
bjcount said:
Here are the 6d,s17 numbers from the ev chart:
Which mistake is the biggest blackjack mistake in terms of EV?
Not hitting 12 vs a 7
(ev= -0.477)
not splitting 8,8 vs a 7 (ev= -0.48)
not hitting 16 vs 10 (ev= -0.536)
not hitting 12 vs a 10 (ev= -0.540)

Playing the hand correctly using BS:

12 vs 7, hit = ev -0.27
8,8 vs 7, split = ev +0.319
16 vs 10, stand= ev -0.54 / hit= ev -0.534
12 vs 10, hit= ev -0.375

than 8,8 vs 7 is clearly the largest mistake we could make.

hand probability:
12vs 7 (t,2 vs 7) 0.003677
8,8 vs 7 0.00044
16 vs 10 (t,6 vs 10) 0.014553
12 vs 10 (t,2 vs 10) 0.014553


based on frequency 12 vs 10 is the overall costliest mistake.
BJC
But the point is, we're talking about "mistakes." None of us is going to make such a mistake frequently, if ever. Therefore, I don't think frequency should be part of the solution. On the other hand, splitting 8's should never come up. How can one forget to split 8's? To forget to split 8's, you must be three sails to the wind! Please don't drink and count.
 

callipygian

Well-Known Member
aslan said:
How can one forget to split 8's?
This reminds me of my ploppy days. One of my friends could just not get down basic strategy, so we oversimplified it down to a few rules:

1. Hard hands
a. dealer 2, 3, hit to 13
b. dealer 4-6, hit to 12
c. dealer 7-A, hit to 17
d. double 11 vs. dealer 2-T
e. double 10 vs. dealer 2-9

2. Soft hands
a. hit to soft 18
b. double A3-A7 vs. dealer 5-6

3. Split hands
a. always split 8's
b. always split A's
c. don't split anything else

4. Insurance
a. NO

Despite all this, there wasn't a single rule on this list he didn't forget or screw up at one point, perhaps except insurance - not doubling 11 vs. dealer 6 ("Dealer 6 is bad, right?"), not splitting A's ("Soft hands hit to 17, right?"), etc.

Ironically, once he got BS down he became one of the best counters because he was the first one of us who could talk while keeping the count. We still mock him when we're at a BJ table together ... when dealer shows a 6, inevitably someone will ask, "dealer 6 is bad, right?"
 

aslan

Well-Known Member
callipygian said:
This reminds me of my ploppy days. One of my friends could just not get down basic strategy, so we oversimplified it down to a few rules:

1. Hard hands
a. dealer 2, 3, hit to 13
b. dealer 4-6, hit to 12
c. dealer 7-A, hit to 17
d. double 11 vs. dealer 2-T
e. double 10 vs. dealer 2-9

2. Soft hands
a. hit to soft 18
b. double A3-A7 vs. dealer 5-6

3. Split hands
a. always split 8's
b. always split A's
c. don't split anything else

4. Insurance
a. NO

Despite all this, there wasn't a single rule on this list he didn't forget or screw up at one point, perhaps except insurance - not doubling 11 vs. dealer 6 ("Dealer 6 is bad, right?"), not splitting A's ("Soft hands hit to 17, right?"), etc.

Ironically, once he got BS down he became one of the best counters because he was the first one of us who could talk while keeping the count. We still mock him when we're at a BJ table together ... when dealer shows a 6, inevitably someone will ask, "dealer 6 is bad, right?"
Priceless!
 

Kasi

Well-Known Member
I think you may maybe need a "None of the Above" category whether you choose to assume frequencies or not assume them lol.
 
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