Pontoon Basic Strategy: 2 card 9 vs. 3 card 9

[TGoldman]

Could someone please explain the reasoning behind the basic strategy for Pontoon (http://wizardofodds.com/pontoon) that involves hitting on a 2-card 9 vs. doubling on a 3-card 9?

If we're doubling hoping to eventually make a 5-card trick, why not wait to double until after we have more information knowing our 4th card? The other reason would be to double on the strength of the 9, but if that's true why not do it for all 9's and not just 3 or 4-card nines? /images/graemlins/confused.gif Any ideas?

[fluff]

You don't double 2 card 9s probably because you get an extra card automatically if your total is 14 or less, increasing your chance of busting. In BJ, doubling 9s is done in part on the strength of the 9, but also on the fact that you can't bust, but the dealer might (3-6 showing).

For 3 card 9s, you double because now the drawback of busting is compensated by the 2:1 payout of the 5 card trick, and you have 3 cards already.

[TGoldman]

I forgot that the player must hit on all 14s or less. Thanks for the explanation--it makes sense now.