fair odds

fair odds
The odds which would leave anybody betting on a random event with zero expected gain or loss. For example, if there is 1 chance in 100 that my house will burn down during the next year, actuarially fair odds are 99 to 1 against this happening. If I bet £1, which I lose if my house does not burn down, but get £99 if it does, my expected gain is (1/100) (£99) − (99/100) (£1) = 0; the odds are thus actuarially fair.