Glossary

The published set of decisions the edge figure assumes on every hand. Twenty-One Notes covers the decisions themselves.

Used in: What is the house edge in blackjack: the sum, worked in pounds

The pattern of results you get from counting successes over a fixed number of independent tries, each with the same chance of success.

Used in: What is casino house edge and how does it work?, A casino streak looks rarer when you hide the search that found it, A longer casino session changes more than the average loss

A machine that varies the chance of a prize according to results from previous games, as described in the Commission’s return to player guide.

Used in: One or more is not certainty: the sum, worked in pounds

The chance that something does not happen, which is one minus the chance that it does.

Used in: One or more is not certainty: the sum, worked in pounds

The number of occurrences of the event in the sequence.

Used in: How do you read online casino probabilities without confusing the question?

The stake times the house edge, added up over the hands played. An average, not a forecast of any one session.

Used in: What is the house edge in blackjack: the sum, worked in pounds

The average number of occurrences across the whole collection of possible sequences; it does not say the event must occur.

Used in: How do you read online casino probabilities without confusing the question?

The average net cost across all the model's possible results. It is not what any one session loses.

Used in: A longer casino session changes more than the average loss

What a bet is worth on average: the chance of winning times what you win, minus the chance of losing times what you stake.

Used in: What is the house edge in blackjack: the sum, worked in pounds

Expected net loss as a percentage of a stated stake base. Check whether that base includes later wagers in the same round.

Used in: What is casino house edge and how does it work?, A longer casino session changes more than the average loss, What is the house edge in blackjack: the sum, worked in pounds

One outcome carries no information about the next.

Used in: What is casino house edge and how does it work?, How do you read online casino probabilities without confusing the question?

Earlier results do not change the probability of the next trial. Here the word describes the trials, not the overlapping windows built from them.

Used in: A casino streak looks rarer when you hide the search that found it

A trial whose result does not change the chance attached to any other trial.

Used in: One or more is not certainty: the sum, worked in pounds

A named prize whose trigger, eligibility and size are defined in a game’s rules.

Used in: What is casino house edge and how does it work?, A longer casino session changes more than the average loss

A weighted average of monetary outcomes; an expectation, not a missing third prize.

Used in: How do you read online casino probabilities without confusing the question?

The difference between money returned and money staked in the calculation being described.

Used in: An average is not a session forecast, What is casino house edge and how does it work?, How do you read online casino probabilities without confusing the question?, A longer casino session changes more than the average loss

A number from zero to one, often displayed as a percentage.

Used in: How do you read online casino probabilities without confusing the question?

A jackpot pool funded under stated rules, potentially including a seed and a ceiling. Its displayed amount and eligibility can change; consult the game rules.

Used in: What is casino house edge and how does it work?, A longer casino session changes more than the average loss

A blackjack hand that neither side wins; the stake is returned.

Used in: What is the house edge in blackjack: the sum, worked in pounds

The share of the money staked that is returned as prizes, averaged over a very large number of game plays.

Used in: One or more is not certainty: the sum, worked in pounds, What is casino house edge and how does it work?, What is the house edge in blackjack: the sum, worked in pounds

Expected gross prizes as a percentage of stakes. With the same scope and stake base, it equals 100% minus house edge.

Used in: What is casino house edge and how does it work?

A monetary expectation: the average share of stakes returned over a very large number of plays. It is not the probability p of one outcome.

Used in: A longer casino session changes more than the average loss

The Gambling Commission's remote gambling and software technical standards. RTS 7 covers the generation of random outcomes.

Used in: What is casino house edge and how does it work?, A casino streak looks rarer when you hide the search that found it

The Gambling Commission's technical standard on the generation of random outcomes in covered remote products.

Used in: A longer casino session changes more than the average loss

A statistical test, described by NIST, that examines a whole defined sequence for non-randomness rather than one eye-catching patch.

Used in: A casino streak looks rarer when you hide the search that found it

Asking an operator, or a scheme such as GamStop, to block you from gambling for a set period.

Used in: What is casino house edge and how does it work?

What each trial pays back for each outcome. Here, £2 back including the stake with probability 0.49, otherwise nothing.

Used in: A longer casino session changes more than the average loss

How far a session can stray from the average; the statistician’s variance, shown on this page as one standard deviation.

Used in: What is the house edge in blackjack: the sum, worked in pounds

The amount put at risk in a particular bet.

Used in: One or more is not certainty: the sum, worked in pounds, An average is not a session forecast, What is casino house edge and how does it work?, A casino streak looks rarer when you hide the search that found it

The square root of the probability-weighted mean squared distance from the expected result. It has the same units as the result and is not a maximum loss.

Used in: What is casino house edge and how does it work?, A longer casino session changes more than the average loss, What is the house edge in blackjack: the sum, worked in pounds

What a bet would have to pay to be exactly fair, given how many equally likely outcomes there are. Paid odds are what the game actually pays.

Used in: What is casino house edge and how does it work?

The total amount staked across all trials. A returned stake that is staked again counts again, so turnover is not fresh money deposited.

Used in: A longer casino session changes more than the average loss

How widely results scatter around their average. Its square root is the standard deviation.

Used in: What is casino house edge and how does it work?

How much a game's results swing around its average; a slot site's word for spread.

Used in: What is casino house edge and how does it work?

A condition specifying a total value of qualifying bets before specified funds become withdrawable.

Used in: What is casino house edge and how does it work?

Offer conditions specifying a required amount of qualifying stakes and how those stakes are counted. This page does not model promotions.

Used in: What is casino house edge and how does it work?

A block of three consecutive positions within the six-result history. Four such windows exist, and neighbouring windows share two trials.

Used in: A casino streak looks rarer when you hide the search that found it

A request to transfer eligible funds out of an account through a supported method.

Used in: A longer casino session changes more than the average loss