Outcome bias
What does "outcome bias" mean in sports betting?
Judging a decision by how it turned out instead of by what was known when it was made. Also called resulting.
Psychologists Jonathan Baron and John Hershey showed in 1988 that people rate the same decision as better when it happens to work out, even when they agree the outcome shouldn't matter. Former poker pro Annie Duke calls this habit "resulting."
In betting, a single win or loss says little about whether a bet was smart. Grade the price you got, your estimate and the closing line first. Look at the result separately, and only trust results across large samples.
Example
You bet at -110 and estimate a 55% chance to win. Expected value is (0.55 x $100) - (0.45 x $110) = +$5.50 per $110 bet. It loses. Grading on the result calls it a mistake, yet 100 bets like it would be expected to profit about $550.
Related terms
Expected value (EV)
Expected value (EV) is the average amount a bet would win or lose per play if you could make it many times. Positive EV (+EV) means the price is better than the true chance.
Closing line value (CLV)
Closing line value (CLV) measures whether you got a better price than the final price before the game started. Beating the closing line consistently is one of the best signs of a real edge.
Gambler's fallacy
The mistaken belief that a random streak has to even out soon, so a result is 'due' after it hasn't happened for a while.
Recency bias
The habit of giving the latest games or results more weight than they deserve when you predict what happens next.
Research tools
Free. Hit rates show past results, not a prediction. 21+.
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