Why Same-Game Parlays Are Different
A same-game parlay combines legs from a single game. Because those outcomes influence each other, the standard multiply-the-probabilities math no longer applies cleanly.
The short answer
Legs from different games are usually close to independent. Legs from the same game are not: the game script connects them. A favorite covering a large spread makes the over more likely; a starting pitcher going deep into a game connects to strikeout totals, team totals, and the moneyline all at once.
How sportsbooks price them
Books know legs are correlated and price same-game parlays with internal models plus an additional margin layer. The result is typically a payout shorter than multiplying the individual prices would give. Some of that adjustment reflects real correlation; some of it is simply extra vig that is hard for a bettor to see.
How to think about them honestly
Same-game parlays are not automatically bad, but they carry two extra costs: correlation you cannot easily compute, and margin you cannot easily see. EVScout flags same-game correlation and lowers the confidence of the evaluation rather than inventing a precision that does not exist.
Try the math yourself
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EVScout applies this math to every leg of your parlay automatically — estimated fair odds, estimated EV, sportsbook margin, and correlation warnings.
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