The effect of card removal at the game of Blackjack, and counter measures casinos employ to prevent exploitation by players in Australia.
By Andrew MacDonald
Gaming Manager, Casino Operations, Adelaide Casino, 1994
Brief Overview |
Card Counting Legalities (Precedents) |
Counter Measures |
Profit Analysis |
Sensitivity Analysis (%profit) |
Blackjack Simulation- Experiment- December 1990 |
Experiment Conclusion |
Blackjack, unlike most other casino games, is a game which involves varying
degrees of skill depending upon an individual player's competence. This is due
in large part to the fact that the probabilities associated with the game vary
whenever a card is removed from the shoe, and that players may vary their play
This really is a direct contrast to other casino games which have a constant
in-built house percentage. For example, on single zero Roulette where each spin
is an independent event, it is of no concern to the player that, for example,
15 blacks have been spun consecutively, the odds of black being spun again are
still 18-19, ie, fractionally less than even money. Therefore, there is no such
thing as a good or bad Roulette player, only lucky or unlucky players in the
short term. In the long-term, if measured over a considerable period of time,
the player should lose 2.70% of his turnover on Roulette. The house percentage
on most casino games is between 1 and 28%, with table games (excepting Blackjack)
averaging around 4% and Keno being around 26% on average.
With the use of good basic strategy at Blackjack, however, the house percentage
fluctuates, rarely to a large extent, between approximately +3 and -3 percent.
This, of course, means that if a player could determine when the house percentage
was negative and only place bets under those circumstances or greater sized
bets, then over a long period of time that player would win. The amount won
would be determined by the extent of the player's advantage related to the amount
of turnover from that player.
This system of play has been developed and is called "card counting". The development
of card counting was pioneered in America, utilising computers and software
development for the simulation and analysis of Blackjack play.
This determined that the house percentage was directly related to the relationship
of high cards (10,J,Q,K,A) to low cards (2,3,4,5,6) and that when this relationship
showed an increase in the number of high cards in the remaining decks then the
house percentage decreased. Such a deck is said to be 10 rich and in favour
of the player.
To determine whether a deck is ten rich or not various systems have been developed
with varying degrees of complexity and efficiency. A simple yet effective method
is the Braun Plus Minus Count. In this count system the cards 10,J,Q,K and Ace
are assigned a value of -1 with the cards of low value (2,3,4,5, and 6) being
assigned a value of +1. The cards 7, 8 and 9 are prescribed no value.