I have been trying to write my own blackjack simulator, and have noticed something that seems a bit strange to me. Almost everytime I run it, (with one player only), the player gets significantly more blackjacks than the dealer. Is there an obvious reason for this that I can't see, or is it looking like being a bug I need to track down?
Regards,
Stuart
...The guy who gets all the blackjacks that Frank "The Flaw" Stanton doesn't get. :)
Do you finish the player's hand before you assign a value to the dealer's hole-card? Will you even know what the dealer's hole-card was if the player busts? Or do you simply chalk up a player bust without playing out the dealer's hand?
I would include a counter to make sure the number of player hands always exactly matches the number of dealer hands. Don't treat the two hands (player and dealer) as "one hand". Tally each independently, then tally them together if you like.
Did you allow for the fact that some of the time, both the dealer and player get a blackjack on the same hand? Did you give the dealer credit for his, too, or did you just increment an automatic win for the player, instead of a push?
Did you assign the exact same variable-type to each counter? Do the counters both increment at the same spot in the program (within the same loop)?
The way I have been playing it is that the dealer is only dealt one card (face up) and their hand is only played out if the player doesn't bust. In other words, the dealer doesn't have a hole card at all.
The idea of tallying the dealer/ player hands separately is a good one. At one point I thought I had found the bug in that I was incorrectly counting 21s after a split as blackjack, but even after fixing this, the ratio of blackjacks was still at least 3:2 in favour of the player.
I checked the code that handles both the dealer and player getting blackjack, and they are both counted, although it is not paid. This code is in a single 'determine_result' function that is called from the main game loop, so it should be okay. I did a search for the counter variables and they definitely don't appear anywhere else in the program.
Thanks for taking the time to make your suggestions. I will do as you recommend and gather some hand statistics for the dealer separately and see if that sheds any light on what is going on.
Thanks again,
Stuart
The idea of tallying the dealer/ player hands separately is a good one. At one point I thought I had found the bug in that I was incorrectly counting 21s after a split as blackjack, but even after fixing this, the ratio of blackjacks was still at least 3:2 in favour of the player.
The dealer gets a natural approximately once per 21 hands. The player gets a natural approximately once per 21 hands. With that hint, you should be able to narrow the bug down to dealer or player.
Stanford Wong
As the dealer is never dealt a second card if the player busts, (and with the 21-after-split bug fixed), the ratio is starting to look quite even:
For example, after 1000 rounds, the player has had 1000 chances at receiving blackjack, but having busted 156 times, the dealer only has 844. In the end the stats showed:
PLAYER BLACKJACKS: 43 (one every 23.2 hands)
DEALER BLACKJACKS: 34 (one every 24.8 hands)
Presumably the absolute figures will even out in a game with more players, with the ratio of blackjacks per hand staying about the same.
Perhaps I should have gone to a casino at least once before trying to write a simulator... ;)
where ever I play They get all the blackjacks.
give the dealer a hole card and write a peek() function?
P.S. I visited your page, where's the source? I wasn't able to find it and would like to take a look at it.
In the end I want to make the simulator completely configurable with different house rules. This way the player will be able to choose whether the dealer has a hole card or not.
As my experience with blackjack (particularly variations not common in Australia) isn't incredibly extensive, this is all going to be a bit of a learning excercise for me.
The source is currently available from CVS repository on Sourceforge:
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/jacl/
If you are unable to access CVS, I can email you the source.
Obviously some sort of 'Murphy's Law' function will be required... ;)
Not peeking would not properly simulate a game where the dealer peeks and will skew the number of blackjacks as you're seeing. How about:
If noDealerHoleCard = 0 then peek()
