Mike Whalen: Blackjack Basic Strategy

[Mike Whalen]

I have long used the basic Strategy when playing BJ but I am beginning to question the odds of hitting 15 & 16 against the dealer's 7-A. Here's my logic.
When you hold 15 there are 7 cards (7-K) that can bust you yet only 5 cards (2-6)that can do you any good.
(I disregard the Ace since it is of no real advantage here). This makes your odds of getting a value card only 38.5% (5/13) vs 53.8% (7/13)of busting. If you also omit the 2 which only gives you 17; then the odds of getting a value card drop to 30.7%. In the case of hitting 16 the odds are even worse-only a 30.3% chance of getting a value card. Even hitting a 14 is no bargain since you again have only have 5 value cards to catch (3-7) vs 6 cards (8-K) that can bust you (again omitting Ace & 2 which do you no good. Slightly better odds but still less than 50%.

Does anyone agree with my logic or am I missing something?

[Norm Wattenberger]

A few things:

1. You can draw more than one card with a 15.
2. You need to consider all possible dealer hand conclusions and their frequencies; not just your own. The point is not just to improve your hand but to beat the dealer's hand.
3. You need to exclude the cards in your hand from the probability calcs. That's all combinations of 15 and their frequencies. Also exclude the dealer card.

You are right you are probably screwed drawing to a 15 against a ten. But, the odds are even higher that you're screwed if you don't. Trust Basic Strategy. Unless you got it from a John Patrick book.


Blackjack Scams

[Mike Whalen]

1) I'm not sure what you mean when you say you can draw more than one card with a 15. Can you elaborate.
2) Obviously with this strategy I'm not assuming that the dealer always has a 10 count card in the hole. If that were the constant assumption then it would make sense to hit 15 or 16.
3) Sure but that would change the odds only marginally.

A few things:

> 1. You can draw more than one card with a 15.
> 2. You need to consider all possible dealer hand
> conclusions and their frequencies; not just your own.
> The point is not just to improve your hand but to beat
> the dealer's hand.
> 3. You need to exclude the cards in your hand from the
> probability calcs. That's all combinations of 15 and
> their frequencies. Also exclude the dealer card.

> You are right you are probably screwed drawing to a 15
> against a ten. But, the odds are even higher that
> you're screwed if you don't. Trust Basic Strategy.
> Unless you got it from a John Patrick book.

> Blackjack Scams

[Parker]

It is a mistake to try to reason out basic strategy, at least if you don't have a PhD in math. Many plays are counter-intuitive.

The first thing to understand is that if we are holding a stiff vs a strong dealer upcard, we have a losing hand. No play is going to turn it into a long-term winning hand. All basic stategy will do is minimize the loss.

With a stiff hand, the only way we win is if the dealer breaks. Against strong dealer upcards, our odds are not good. Even if we only improve our hand to a 17, we have at least introduced the possibility of a push, thus greatly strengthening our hand.

The only way to really see this is to compare the EV of each action. In Blackjack Attack, 3rd Edition, by Don Schlesinger, we will find the most comprehensive and accurate basic strategy tables available in print anywhere. These take into account every possible card combination.

Let's take a look at one example, say 15 (T,5) vs dealer 10 (6D, S17). We find the following EV's:

Std: -.540055
Hit: -.503907

We now see that for every dollar wagered, we will lose, on average, 54.0055 cents if we stand, but only 50.3907 cents if we hit. So, we hit. Also note that we lose more than half our bet either way, so we would surrender if available.

Blackjack Attack is available from our online catalog, along with a lot of other really cool stuff.

[Norm Wattenberger]

Assume nothing. The dealer may very well have a five in the hole. And then draw another five. All possibilities must be considered according to their frequencies. When you add them all up, you can see which decision makes sense. Parker's post gives an example.

> 1) I'm not sure what you mean when you say you can
> draw more than one card with a 15. Can you elaborate.
> 2) Obviously with this strategy I'm not assuming that
> the dealer always has a 10 count card in the hole. If
> that were the constant assumption then it would make
> sense to hit 15 or 16.
> 3) Sure but that would change the odds only
> marginally.

> A few things:

[OldCootFromVA]

> This makes your odds of getting a value card
> only 38.5% (5/13) vs 53.8% (7/13)of busting.

> Does anyone agree with my logic or am I missing
> something?

What you're missing is considering the dealer's probabilities. IOW, it's not just YOUR hand, it's your hand AND the dealer's hand.

This is an oversimplification (to put it mildly), but when the dealer shows a Seven, he will make a hand about 74% of the time. So if you stand your 15 or 16 vs 7, you will lose 74% of the time for sure. But you only have a 54% chance of breaking the hand it you hit; so why not hit?

And this is against the Seven, the dealers chances of making a hand go up as his card goes up, until it reaches about 83% when he shows an Ace.

[Norm Wattenberger]

See http://www.qfit.com/CVDPC.htm