Terminology

We've used a few terms so far that relate to the Tracker. Before we start explaining how the Tracker works, let's lock down a definition on:

Bet/Selection/Proposition/Outcome: These terms are often used interchangeably to refer to a betting opportunity in a market. You place a bet on a specific outcome, which is also called a selection or proposition.
Market: A market is a collection of propositions that you can bet on. For example, a head to head market in an AFL match lets you bet on the outcome of the match between two teams. Each team would be a proposition in the market.
Stake: The amount of money you choose to bet on a particular selection. This is also known as your bet size.
Odds: Odds determine how much you can win from a successful bet. They also represent the bookmaker's implied probability of that outcome occurring, where this probability is denoted as 1 divided by the odds.
Fair Odds: Fair odds are the implied true probability of an outcome occurring, based on the actual likelihood of that outcome. They are calculated by taking the inverse of the true probability (that is 1 divided by the true probability). We'll cover how we calculate true probability in a later course.
Expected Value (EV): Expected value is the difference between the true probability of an outcome occurring and the implied probability represented by the odds. A positive EV indicates a long term profitable bet. That is, if you consistently place bets with a positive EV, you should, in theory, make a profit over time. A bet with a positive EV does not, however, guarantee a win on any individual bet.