Did I make the right move?

Nice posts,
I noticed that in this thread a subject of comparing total wins for doubling or standing on a pat hand has had arisen. In this particular case, gronbog’s usually helpful sim shows that it is almost identical – which at first glance may seem counter-intuitive.
We can also get those numbers by a simple procedure of comparing only gains and loses for both actions.
Note that for dealer’s bust upcards (2-6) her final total results of 17 to 21 are very similar between 11% to 13% (and for the dealer upcard 4 [s17] it varies from 11.3 to12.6%.
We can treat them as the same value, let’s call it P.
When we double A7, instead of having 18 vs. dealer all results, we will consider every hit card as C (1/13th).
We have 5 cards (5C) that make our doubled hand a stiff, one C hand of each 17, 19, 20, and 21. We also get 4 C’s when doubled card is a Ten, keeping our total as if we stood on 18, which can be omitted; it doesn’t change percentage of wins.
Let’s look at the gains and loses for total percentage of won hands.
The loses:
The stiff hands (5C) win with the dealer’s bust but lose to everything else, standing on 18 wins with bust and d’s 17 – the only difference is d’s 17, so the loses are 5C x 1P.
Our double becomes 17 (1C), it wins only with d’s bust – our 18 would win with d’s bust and d’s 17. The difference is 1C x 1P
Total loses (5C+1C) x P = 6 CP
The gains:
Doubled hand is 19 (1C) wins improve over having hand of 18 by winning vs. d’s 18, so we have 1Cx 1P
Doubled hand is 20 (1C) wins improve over having hand of 18 by winning vs. d’s 18 and 19, so we have 1C x 2P
Doubled hand is 21 (1C) wins improve over having hand of 18 by winning vs. d’s 18, 19, and 20, so we have 1Cx 3P
Total gains 1CP+2CP+3CP = 6 CP
Gains and loses are about equal therefore the total percentage of wins will the same regardless standing or doubling.

I know that my explanation is somewhat clumsy but once you practice this technique it is fast and can be used in many situations.

S. Yama

 

Thanks Yama. I love these "human" simulations.

 

Since blackjacks pay even money, is it wise to double every single one I get?? (save maybe against aces)
And what about splitting tens? I couldn't find a table of %s of wins after splitting...

 

Oh here it is:
http://wizardofodds.com/games/blackjack/appendix/1/

Maybe splitting 10s against 5 and 6 is a move one can consider in a tournament setting?

 

In majority of situations you should treat bj as a winning hand, especially before the last couple hands.
Let’s say dealer shows the easiest to beat 6. If you take even money blackjack you win 100% of your bet. If you double your bj, you win 63.4% (x2) and lose 29.9% (x2), your net win is only 67% of your bet.
There may be situations where doubling on bj is a better play, but they will be rare.
For example, first that came to me for no specific reason and betting is not necessary optimal, could be, next-to-last hand, in order of betting:
BR3 – 23K, BR2 (you) – 41K, BR1 – 53K
BR3 bets first 24K – all-in,
You, as BR2, bet 13K from 41K brl to keep more chips than BR3, even if you lose and he pushes, and losing that bet leaves you with more than half BR1’s brl if he pushes or loses. That 13K bet is also more than the gap to BR1, who bets only 5K to cover your single win, and would have more than 2K lead to BR3, even if he (BR1) loses and BR3 wins.
BR3 busts, you get bj, BR1 has 20, and dealer shows 6.
If you stay you overcome BR1 going to the last round if dealer makes 20 or 21; otherwise you are second, betting first on the final hand.
If you double and win you are going to be a leader going the last hand, even if BR1 splits/doubles his bet and wins.
If you take the bj you advance about just over 34%, if you double you advance almost 38%.
As you can see even somewhat extreme situation doesn’t make much difference.
Of course there may be other scenarios; e.g. you would double your bj if you have only one opponent who has less chips than you and is all-in with a stiff hand – but you would do so with any non-busting hand if didn’t bet exactly half of your stack.

Don’t see any difference for playing/splitting TT, than in other blackjack tournaments.

S. Yama