I received a question from a member of our website recently asking why some of the numbers on our deviation chart are different from what they have seen in another book or website.
Deviation charts can vary slightly, depending on
1. the rules, number of decks, penetration, etc that you’re assuming
2. your strategy for calculating the true count
3. the number of hands that you ran your simulation generator for
We ran our deviations based on the games that we most commonly played and how we calculate the true count. We ran a ridiculously long simulation. So I trust it’s accuracy. Also, keep in mind that the net effect of slight deviation differences between one chart and another are most likely fractions of pennies on the dollar. So if one chart says stand a 12 v. 3 at 2, and another says stand a 12 v. 3 at 1, the actual number may be something like 1.5, so there’s not a massive difference between the 2. You shouldn’t see different themes in deviations. For example, if our chart says to split 10′s against a 6 at a true 4 and above while another chart says to split 10′s only at negative counts, then there’s something wrong with the other chart!
Hope that helps clarify!
Hi, almost all of your deviation chart entries make sense and I’m sure are correct, however in hard totals section 14 vs. A shows index of 10 and 14 vs. 10 shows hit. Naturally I would assume a smaller index for 14 vs. 10 and I’d like to know what it is.
Best regards, Val.
Val,
Yeah, let me try to explain one way of thinking about it… By the way, this is the same concept as why you would Double down a 10 v. A at +3, but wait until +4 to double 10 v. 10. So here’s the logic:
In US blackjack, if the dealer has an Ace up, the first thing they’ll do is check for a blackjack. If they have a blackjack, you’ve already lost. So by the time you get to this index number, you know the dealer doesn’t have a 10-value card underneath. There’s still a 1/9 chance they have a 9, giving them a 20, but the rest of the time, they’ll have less than 20.
If the dealer has a 10 up (we also will know by now they don’t have a blackjack, or the hand would be over), there’s more than a 1/3 chance they have a 10 underneath for a 20. So you are actually in a slightly worse situation with a 10 v 10 than a 10 v A.
*Obviously, there are many other combinations of hands the dealer can make, but the idea is that, with an Ace up, odds are the dealer WON’T have 20. With a 10 up and a high count, the odds are much more likely that the dealer has a 20.