Errata corrections published before Snyder?s review of McDowell?s BJAP.

Errata for Blackjack Ace Prediction

Page 114, Line 15: At this point we invoke Snyder?s rule of thumb?the player and the dealer share the Aces 50/50. In this case, that means the player and the dealer get three additional aces each. The probability of the Ace ?hitting the money? P(h) and the probability of the dealer getting the Ace by accident P(d) become 0.10 while P(m) is reduced from 0.87 to 0.80.

Page 114, Line 25: Assuming E1 = +0.51, E2 = -0.34, E3 = -0.005 h = 0.10, d = 0.10 m = 0.80
E(X) = (+0.51 X 0.10) + (-0.34 X 0.10) + (-0.005 X 0.80)
= +0.051 - 0.034 - 0.004
= +0.0130

Note, if the dealer can be prevented from getting the Ace, the player?s expectation is:
E(X) = (+0.51 X 0.13) + (-0.34 X 0.07) + (-0.005 X 0.80)
= +0.0663 - 0.0238 - 0.004
= +0.0385

Michael
Dalton
Digitally signed by Michael Dalton
DN: CN = Michael Dalton, C = US,
O = Blackjack Review Network, OU
= Spur of the Moment Publishing
Reason: I am approving this
document
Date: 2004.10.24 16:40:23 -04'00'

Inferences:

1) Arnold published his review without being aware of the author?s changes, which were available for free through the publisher?s web. Note that 1.3% is not 4.2% precisely. This last figure was used extensively during his McDowell?s folly review as one of his argumentative weapons.

2) Unfortunately David 7-3 formula still remains inaccurate, due mainly to the E3 value underestimation, as I tried to explain a reader below.

Both figures, that is, sharing the final probabilities of getting the keyed ace with the dealer and preventing him from getting it, can be extracted accurately with an exact combinatorial and/or simulated approach.

Moral? Math and hurries aren?t good partners.

Hope this helps

Sincerely

Zenfighter.