Part III: Business & Regulation · Gambling Mathematics & Probability

15. Dependent Events

Foundational Probability

Events are dependent when the outcome of one affects the probability of subsequent outcomes. In casino gaming, blackjack is the primary example of a game with dependent events — as cards are dealt from the shoe, the composition of remaining cards changes, altering the probabilities of future hands. This dependency is what makes card counting possible and is why casinos use multiple decks and shuffle before all cards are dealt. Other games with dependent events include baccarat (card removal from the shoe) and certain poker variants. Surveillance teams must recognize that dependent events create opportunities for advantage play that do not exist in games with independent events.

In practice

The degree of dependency increases as more cards are dealt without shuffling. This is why deck penetration (the percentage of cards dealt before reshuffling) is a critical factor in blackjack advantage play.

One entry from the Casino Industry Glossary — 1,157 terms written for surveillance, compliance and operations professionals rather than for players. Definitions describe industry usage; where a term carries a regulatory meaning, verify against the instrument that governs your jurisdiction.