The actual estimated likelihood of an outcome, with the bookmaker's margin removed.
True probability (or fair probability) is the estimated actual chance of an outcome occurring — as opposed to the implied probability from market odds, which includes the bookmaker's vig.
De-vigging methods like multiplicative, power, additive, and Shin each produce different true probability estimates from the same odds. The choice of method matters more in lopsided markets.
In prediction markets, contract prices are closer to true probabilities since fees are typically lower and more transparent than sportsbook vig.
The probability of an outcome implied by the odds. Includes the bookmaker's margin (vig).
VigThe bookmaker's built-in commission. The difference between true odds and what you're offered.
OverroundThe total implied probability exceeding 100% across all outcomes in a market — the bookmaker's total margin.