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Table Games Cash value of BJ mistakes

Discussion in 'Table Games' started by mike_m235, Feb 3, 2013.

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  1. mike_m235

    mike_m235 Tourist

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    Inspired by another thread and the fact that I'm a total nerd, here are some common 'mistakes' people make at blackjack. We all know the mistakes, but what do they cost?

    For the purpose of this discussion, I'm working off of a $10 bet. It's all linear, so if you bet $100, simply multiply the mistake value times 10. This is based on a neutral count deck. I'm not figuring out numbers for specific counts.

    EV is expected value. That is, if you play this hand a million times, your average return.

    Player 16 vs dealer 10 showing

    Hit EV is $4.60
    Stand EV is $4.60
    Surrender EV is $5.00 (obviously)

    In this example you surrender unless you can't. If you can't surrender, to figure out the difference you have to take it to a third decimal place...meaning your 'mistake' is costing you less than a penny. 6 tenths of a cent, to be exact. So you should hit, but if you don't, I wouldn't worry about it.

    Player 16 vs dealer 7 showing.
    Hit EV: $5.85
    Stand EV: $5.25

    This one is for my brother, who likes to stand on 16 vs a dealer 7. The mistake costs you 60 cents...it's actually more wrong than standing on 16 v a dealer 10, which is kind of counterintuitive


    Splitting 10s vs a dealer 6

    Stand EV: $17.04
    Split EV: $14.68

    Never split 10s. Ever.


    Not splitting 8s vs a dealer 10

    Hit EV: $4.60
    Stand EV: $4.60
    Surrender EV: $5.00
    Split EV: $5.19

    I hate splitting 8s vs a dealer 10. A lot of people do. And surrendering isn't a huge mistake at 19 cents. But the correct play is to split them. For the record, it's even a bigger mistake not to split them against a dealer Ace.


    I'll post a few more in another post. If you've got one that you want to know, feel free to ask it. I've got a spreadheet to calculate it. As I may have mentioned before, I'm a total nerd.
     
  2. KimberlyJ

    KimberlyJ Low-Roller

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    wow, you must be bored:licklips:
     
  3. mike_m235

    mike_m235 Tourist

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    Doubling or hitting with A4 vs a dealer 4

    Hit EV: $10.59
    Double EV: $10.58

    I include this hand because it's the hand on which I most often forget what I should do. Turns out, it doesn't really matter that much. Just a penny. So my advice for playing this hand...if you're feeling lucky, double.
     
  4. mike_m235

    mike_m235 Tourist

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    Little bit, yeah. It doesn't really take me that long.
     
  5. Kickin

    Kickin Flea

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    I like doing the same thing. Also wrote a simple VBA script to simulate basic strategy using an excel EV table and a positive betting progression (1-3-2-6). But you can get all the EVs right here:

    http://wizardofodds.com/games/blackjack/appendix/1/

    The main takeaway in my opinion is to look at the doubles and splits where you have a positive EV greater than 2x the alternative play and then asking yourself why anyone would pass on those opportunities or double for less!
     
  6. mike_m235

    mike_m235 Tourist

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    The wizard is great for the odds. I just find it more enlightening to turn the odds into dollars and cents.
     
  7. nostresshere

    nostresshere Mr. Anti Debit Card

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    I like this idea. Alot.

    For those that are "challenged" or "blitzed" or "____", it would be nice to know which decisions, if wrong, are a minimal cost.

    Personally, I could care less about mistakes that are a partial penny, or even a few pennies. Heck even a dime on a $10 bet is not worth the few memory cells I have left.

    You know those basic strategy cards they sell or you find online? It would be nice to have one that just blanks out those hands that can go either way give or take a few percent.
     
  8. mike_m235

    mike_m235 Tourist

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    Surrendering a 15 vs a dealer 10

    Hit EV: $4.96
    Surrender: $5.00

    Just a four cent mistake to not surrender.
     
  9. Kickin

    Kickin Flea

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    It's the same thing. He shows expected returns, so just multiply it by your bet size if you want the dollar value.
     
  10. lvmb

    lvmb Low-Roller

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    Thanks for the interesting perspective on this.

    One thing I'm struggling a little to understand is this;
    Won't the answers be slightly different under genuine game conditions? Most games I play now on the strip are H17 and they aren't infinite decks constantly shuffled.

    For one of the initial situations quoted A-4 vs 4 the Wizard has the correct play as Double when you use the tailored strategy for 4 or more decks, H17 etc.
     
  11. mike_m235

    mike_m235 Tourist

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    Absolutely. But even then, your value is going to be very close to even, so it's not a huge mistake either way, regardless of conditions.
     
  12. Vimes

    Vimes Tourist

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    I'd like to see 12 vs dealer 2 or 3. This is the one I think least often see players play correctly. Or I have people grumble when I play it correctly.
     
  13. WrongWayWade

    WrongWayWade VIP Whale

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    For 6-deck H17:

    T2 vs. 2: hit: -0.25222 stand: -0.28944 diff: 0.03722 units
    T2 vs. 3: hit: -0.24892 stand: -0.23168 diff: 0.01724 units

    So on a $10 bet you're giving up 37 cents or 17 cents respectively by standing.
     
    Last edited: Feb 6, 2013
  14. mike_m235

    mike_m235 Tourist

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    I've got something way different. I think you're off by a factor of 10.

    12 vs a dealer 2:
    Hit: Expected value is $7.47
    Stand: Expected value is $7.07

    So I've got it at 40 cents on a ten dollar bet.

    12 vs a dealer 3 is closer

    Hit: EV is $7.66
    Stand: EV is $7.47

    So 19 cents.
     
  15. WrongWayWade

    WrongWayWade VIP Whale

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    Yea, dropped a decimal point. From my chart it's 37 cents and 17 cents.

    Depending on the game, number of decks and the exact hand (T2 is slightly different than 93 or 84, for example), these expectation numbers change a bit.
     
  16. mike_m235

    mike_m235 Tourist

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    Yeah, being a couple cents off on a $10 hand calculation is going to be normal...I was calculating for a S17 game, you were using H17. H17 is probably more accurate for a $10 game since you can't find S17 at those limits.
     
  17. Vladimir

    Vladimir Low-Roller

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    I love maths (I'm a nerd!) and this thread is fascinating.

    IIRC the Wizard suggests standing on a 3 card 16 (hitting a 2 card 16), I wonder what is the mathematical advantage for this (I would assume extremely minimal)?

    Another couple, just in case you get time:
    A7(or A34) vs. Dealer T
    55 vs. 6 (interested in Split vs DD)
    11 vs. A
    Soft 21 vs. any dealer up card on a 6:5 game (is DD the correct e/v move?)
    Player 7 or 8 vs. Dealer 6 (e/v for DD vs. Hit)
    17 v Dealer T
     
  18. Nevyn

    Nevyn VIP Whale

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    I would think that is for single deck only? In which case a 3 card 16 means fewer safe cards to draw to.
     
  19. h_upmann

    h_upmann Low-Roller

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    Tell me about soft 18 against 9,10,A. Next to splitting 8's this is the book play I hate the most.
     
  20. mike_m235

    mike_m235 Tourist

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    A7 vs Dealer 10

    Hit EV: $8.56
    Stand EV: $8.22

    55 vs Dealer 6

    Split: $10.45
    Double: $15.76

    11 vs Ace

    Hit: $11.43
    Double: $11.09

    (This one is going to really be affected by your rules on whether the dealer hits or stands on soft 17...more than most...this is for dealer stands on soft 17)

    8 vs Dealer 6

    Hit: $11.15
    Double: $10.87

    7 vs Dealer 6

    Hit: $9.87
    Double: $8.62

    17 v Dealer 10 (not sure why this is a question)

    Hit: $4.16
    Stand: $5.80
    Surrender: $5.00
     
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