House Edge
The mathematical advantage that the casino holds over players in any given game. Expressed as a percentage, it represents the average amount a player loses relative to their total bets over time. For example, a 2% house edge means that on average, the casino keeps 2% of all money wagered. Different games have different house edges, with blackjack typically offering one of the lowest at around 0.5% to 1%, while slot machines can range from 2% to 15%.
Return to Player (RTP)
The percentage of all wagered money that a game returns to players over time. If a slot machine has an RTP of 96%, it means that theoretically, for every $100 wagered, $96 is returned to players and $4 is retained by the casino. RTP is the inverse of house edge. Understanding RTP helps players recognize which games offer better long-term value, though it's important to remember that RTP applies to large sample sizes and individual sessions will vary significantly.
Variance (Volatility)
A measure of how much a game's results fluctuate from expected values. High variance games produce larger swings between wins and losses, while low variance games produce more consistent, smaller fluctuations. A high variance slot machine might deliver fewer wins, but when they occur, they're larger. Understanding variance helps players choose games that match their bankroll and risk tolerance preferences.
Probability
The likelihood that a specific event will occur, expressed as a number between 0 (impossible) and 1 (certain), or as a percentage. In casino gaming, probability determines the odds of specific outcomes. For instance, the probability of rolling a six on a fair die is 1 in 6, or approximately 16.67%. Probability forms the mathematical foundation for all casino games and determines house edge calculations.
Standard Deviation
A statistical measure of how much results deviate from the average expected outcome. In casino gaming, standard deviation helps predict the range of possible outcomes over a given number of plays. A game with low standard deviation produces results closer to the expected average, while high standard deviation indicates larger potential swings. This metric is crucial for understanding short-term gaming experiences versus long-term mathematical expectations.
Expected Value
The average outcome of a bet or game decision calculated mathematically. It's computed by multiplying each possible outcome by its probability and summing the results. If a bet has a positive expected value, it theoretically profits over time; negative expected value means a loss over time. Most casino games have negative expected value for players, which is why casinos profit as a business.