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Casino Bar
Last Update: June 6, 2002

Introduction

Following is my argument that Casino Bar is cheating at blackjack. In May 2002 somebody approached me with what he claimed was a section of computer code he said was taken from the Casino Bar blackjack game. My interpretation of that code is that if the player has a total of 16-21 and the dealer must take a third card, if that hit card will cause the dealer to bust, then it will be rejected and the dealer will get a second chance card. This second chance card is final, whether or not it will bust the dealer. To put it another way here is the logic of the code:

  1. If player has total of 16-21 go to step 2, other wise play normally.
  2. If dealer's 3-card total will be over 21 then go to step 3, otherwise play normally.
  3. Remove dealer's third card, go to step 4.
  4. Take following card from deck, go to step 5.
  5. Take further cards as necessary to attain total of 17 or more, then score hand.

This is what would be known in a real casino as dealing seconds. I do not know what the game does if the player splits and my experiment ignores split hands.

It should be emphasized that I do not know if this code is legitimate.

The Experiment

The goal of my experiment was to disprove that Casino Bar was playing a fair game of blackjack. To do this I designed an experiment to test the frequency the dealer busted on the third card when there was a potential to bust and the player had a total of 16-21. The course of my play this situation happened 332 times. The following table shows how many of these 332 occurences the dealer busted on the third card, according to the dealer 2-card total.

Casino Bar Experiment Results
Dealer 2-card Total Bust on Third Card
Yes No Total
12 11 73 84
13 13 48 61
14 18 49 67
15 21 40 61
16 26 33 59
total 89 243 332

Assuming an infinite deck for the sake of simplicity it is easy to calculate the probability the dealer will bust with any given total of 12-16. With a total of 12 there are 4 cards that will break the dealer and 9 that won't so the probability the next card will break the dealer is 4/13. Likewise the probability of busting on the next card with a total of 13 is 5/13, and so on. The next table shows the expected number of times the dealer should have busted in this experiment based on these probabilities and the number in the sample for each total from 12 to 16.

Casino Bar Experiment Results
Dealer 2-card Total Sample Total Probability of Bust Expected Busts
12 84 30.77% 25.85
13 61 38.46% 23.46
14 67 46.15% 30.92
15 61 53.85% 32.85
16 59 61.54% 36.31
total 332 149.38

Analysis of Results

The number in the lower right corner shows the expected number of busts is 149.38. The actual number of busts was 89. This is quite a disparity. To determine the probability of this disparity I first had to calculate the variance of the number of busts to expect. Using the formula var(x+y) = var(x)+var(y)+2*cov(x,y) we can individually calculate the variance for each total. The covariance is 0 because there should be effect on one hand to the next.

The variance of the binomial distribution, which this experiment follows, is n*p*q, where p is the probability of success and q is the probability of failure. The total variance is then 84*(4/13)*(9/13) + 61*(5/13)*(8/13) + 67*(6/13)*(7/13) + 61*(7/13)*(6/13) + 59*(5/13)*(8/13) = 78.11. The standard deviation is the square root of this number, or 8.84.

The difference between actual and expected dealer busts is 149.38-89 = 60.38. This is 60.38/8.84=6.83 standard deviations below expectations. The probability of falling this far or more to the left of the bell curve is 1 in 238 billion. To put this in comparison the probability of hitting the Power Ball is 1 in 80,089,128. It would be 2976 times easier to win the power ball with one ticket than to have results this bad in a fair game.

Independent Tests

The GameMaster did his own independent test. Of the 223 hands in the GameMaster's sample where the player had 16-21 and the dealer had a 2-card total of 12-16 the dealer should have busted on the third card 100.77 times, but in fact only busted 53 times. The probability of 53 or less busts is 1 in 43 billion. Should there be any doubts the GameMaster videotaped his play.

The webmaster of Custom Strategy Cards also conducted various tests on Casino Bar's blackjack game. The most convincing of which is the distribution of the dealer's third card when the dealer had a 2-card total of 12-16 and the player had 17-21. Following are the results.

Casino Bar
Third Card Distribution
Card Total
A48
254
371
442
546
639
733
836
924
1020
J13
Q20
K15

Note how heavily weighted the low cards (A-5) are compared to the high cards (9-K). Putting this distribution through a chi-squared test the chi-squared statistic is 97.83 with 12 degrees of freedom. The probability of results this skewed are 1 in 676 trillion. Further information about this experiment can be found at www.customstrategycards.com/vnd_coa-we.htm.

Casino Bar Response

Before making this public I gave Casino Bar a chance to respond to my allegations. Here is their reply.

Dear Michael,

Thank you for contacting our support team.

Your Black Jack queries regarding randomness, I will attempt to provide you with layout and the techs of the game, then providing you with facts why we are sure our RNG is perfectly legitimate.

We use 4 decks of cards in the game. These are re-shuffled after every hand, as is the case with most on-line establishments.

The difference between land and on-line in respect of shuffling after every hand and the deck only being shuffled when the shoe comes to and end, is obvious, which I am sure as the experienced gamer that you are, you will understand.

Our BJ game is our main attraction and through an infinite number of players and hands wagered, we have received very few complaints.

Michael, your total gaming odds at CasinoBar are 95%. Research will tell you that this figure is comparative and many instances on a par if not better than most casinos out there.

This above leads me to believe that we offer a reasonable, fair and enjoyable gaming experience.

Please let us know if we can be of further assistance.

Regards,

Kira
Customer Service
www.CasinoBar.com

My response to their response is that their random number generator is not the issue. I'm sure their random number generator is fine. What I suspect is that their programmer deliberately put in code to take a "second chance" card in the situation already mentioned. Regarding the second point I do not dispute that my total actual return is 95%. The way they cheat is subtle and will only lower the theoretical return by a few percentage points in my rough estimation. Casino Bar does claim their overall actual return in blackjack to be 97.68% for the month of April 2002. This figure was evidently calculated in house, no outside verification is mentioned.

Post Script

It should be noted that Casino on Air now uses the same software as Casino Bar. I make no allegations against Casino on Air and simply offer this information for the readers consideration. I think this is a shame about Casino Bar. They have good software, a nice web site, and otherwise seem a good organization.

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