Thanks to some eagle-eyed users, I learned that the Double Down Probability Charts at this site were wrong. When I did the last update to that page to improve readability, I accidentally altered the headings in a way that made the tables inaccurate.
Basically, the dealer upcards across the top of the chart were 2/3/4/5/6/7/8/9/T/A
but the results in the chart actually followed the order
A/2/3/4/5/6/7/8/9/T
If you were looking at a dealer upcard of 2, you were actually seeing results against a dealer Ace. Yikes! The other errors weren't as severe, but still, dealer upcard of 3 was actually 2, etc.
I fixed that today, so the figures are correct.
I apologize for any confusion caused by my error, and offer a big Thanks to those who pointed out the trouble.
Basically, the dealer upcards across the top of the chart were 2/3/4/5/6/7/8/9/T/A
but the results in the chart actually followed the order
A/2/3/4/5/6/7/8/9/T
If you were looking at a dealer upcard of 2, you were actually seeing results against a dealer Ace. Yikes! The other errors weren't as severe, but still, dealer upcard of 3 was actually 2, etc.
I fixed that today, so the figures are correct.
I apologize for any confusion caused by my error, and offer a big Thanks to those who pointed out the trouble.