---
title: "glossary"
url: https://sacstat.org/glossary/
description: "An alphabetical glossary of the probability, game-design and betting-market terms used across the sacstat entries, each linked to the entry that develops it."
---

# glossary

[sacstat](https://sacstat.org/) › Reference › glossary

A – Z

Every term used across the entries, defined once and linked to the entry that develops it. Definitions here are deliberately short; the arithmetic lives in the entries.

## B

bankroll[entry](https://sacstat.org/long-run/#handle)

The sum set aside for play. Distinct from handle: a bankroll can be staked many times over, and the house edge applies to the staking, not to the sum.

## C

combination[entry](https://sacstat.org/lotteries/#combinations)

A selection in which order does not matter. Written C(n,k); the basis of every draw-lottery probability.

## D

decimal odds[entry](https://sacstat.org/foundations/#notation)

A price expressed as the total return per unit staked, stake included. Implied probability is its reciprocal.

dependence[entry](https://sacstat.org/card-games/#memory)

The condition in which one trial changes the probabilities of the next, as when a card is removed from a shoe.

## E

expected value[entry](https://sacstat.org/foundations/#ev)

The probability-weighted average result of a wager, per unit staked. Negative for every commercial game.

## F

fractional odds[entry](https://sacstat.org/foundations/#notation)

A price expressed as profit against stake, such as 5/2. Carries the same information as decimal and moneyline.

free odds[entry](https://sacstat.org/dice/#odds)

A supplementary craps wager paid at the true odds of the point, and therefore the rare wager with an expected value of exactly zero.

## H

handle[entry](https://sacstat.org/long-run/#handle)

The total amount staked over a period, as distinct from the money brought to the game. The denominator of house edge.

hit frequency[entry](https://sacstat.org/slot-machines/#volatility)

How often a machine returns anything at all, independent of how much. A component of volatility rather than of return.

hold[entry](https://sacstat.org/house-edge/#hold)

An accounting figure: the share of money brought to a game that was not carried away. Larger than house edge because money is restaked.

house edge[entry](https://sacstat.org/house-edge/)

Expected loss per unit staked, expressed as a percentage. A property of the payout table, fixed before play.

## I

implied probability[entry](https://sacstat.org/betting-markets/#implied)

The probability a quoted price corresponds to. Across a market these sum to more than one.

independence[entry](https://sacstat.org/variance/#fallacy)

The condition in which one trial tells you nothing about the next. True of wheels, dice and draws; false of card shoes.

## L

law of large numbers[entry](https://sacstat.org/long-run/#lln)

The theorem that the average of independent trials converges to their expectation as the number of trials grows.

## M

moneyline odds[entry](https://sacstat.org/foundations/#notation)

A price expressed relative to a hundred units, positive for outsiders and negative for favourites.

## O

overround[entry](https://sacstat.org/betting-markets/#implied)

The amount by which implied probabilities across a market exceed one. The market equivalent of a house edge.

## P

pari-mutuel[entry](https://sacstat.org/lotteries/#parimutuel)

A structure in which prizes are shares of a pool after a fixed deduction, rather than fixed amounts.

probability[entry](https://sacstat.org/foundations/#counting)

The share of equally likely outcomes in which an event occurs, between zero and one.

## R

random number generator[entry](https://sacstat.org/slot-machines/#rng)

The process that determines a machine outcome at the moment of the request; the animation that follows is presentation.

return to player[entry](https://sacstat.org/house-edge/#rtp)

The complement of house edge: the long-run share of stake returned. Meaningful only over very large numbers of rounds.

rollover[entry](https://sacstat.org/lotteries/#rollover)

A jackpot carried into the next draw, raising that draw's expected value without changing anyone's probability of winning.

ruin[entry](https://sacstat.org/long-run/#ruin)

The absorbing state of an exhausted bankroll, after which favourable variance cannot help.

## S

sample space[entry](https://sacstat.org/foundations/#counting)

The complete enumerated set of equally likely outcomes. Every figure on this site begins with one.

standard deviation[entry](https://sacstat.org/variance/#spread)

The square root of variance, in the same units as the result. Grows with the square root of the number of rounds.

## V

variance[entry](https://sacstat.org/variance/#spread)

The expected squared deviation from the mean; the measure of how widely results scatter around expectation.

virtual reel[entry](https://sacstat.org/slot-machines/#virtual)

An internal list of positions mapped onto physical reel stops, decoupling a symbol's appearance from its probability.

volatility[entry](https://sacstat.org/slot-machines/#volatility)

How a machine's return is distributed between frequent small wins and rare large ones. Independent of RTP.

Return to the [Reference](https://sacstat.org/#entries) index on the reference landing.

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Last modified 17 August 2026.