Spanish 21 - Redouble on 13 v 7?

I'm using the Wizard of Odds Blackjack Hand Calculator to do some strategy checks on Spanish 21. To do that, I use an 8 deck shoe, set the tens to 96 instead of 128 and set it as the composition after the hand is dealt.

When I put in the hand 7-4-2 vs dealer 7 , I get the following probabilities:

Stand: -0.467476
Hit: -0.211781

Since Hit is less than 50% of Stand, and a hit after a double down is not allowed, a redouble on 7-4-2 vs 7 seems to be worth -0.42 in EV and would be preferred to standing. But the basic strategy listed gives the correct play as a stand. What gives?

Ahhh... I figured out the flaw in my logic. The hit odds assume you can hit again. I have to compare the double odds.

EDIT: Sounds like you figured the same things I mentioned here above =).

Quote: tooncestdc

...Stand: -0.467476
Hit: -0.211781

Since Hit is less than 50% of Stand, and a hit after a double down is not allowed, a redouble on 7-4-2 vs 7 seems to be worth -0.42 in EV and would be preferred to standing. But the basic strategy listed gives the correct play as a stand. What gives?

Well, hit is .42 less, but you're also going to double your expected loss by putting more money on the table I'd think?

Let's say you have a $10 bet, that gets doubled... so $20 at risk:

EV(stand) = 20*(-0.4675) = -9.35

A couple things from here:
1) The redouble isn't the same as hitting, unless you have unlimited redoubles. What happens if you redouble and draw an ace and have 14 now? I'd presume you'd be in the exact same scenario... but can you redouble (to affectively 'hit') again? The "hit" figure was more than likely based off a "hit" wherein if you get a poor card you can hit again.

2) Assuming you can re-double, and using the "hit" -0.2118 percentage (which again I don't think is exactly correct here, but might be close enough with unlimited redoubles) you're going to double your negative expected loss, even at the lower range.

EV(redouble) = 40*(-.2118) = -8.47

So now the gap is a LOT closer than you previously made it sound like... So it's really worth only about .04, instead of .42. Lot of things to consider.