What Is Bet Correlation?
Two bets are correlated when the outcome of one changes the likely outcome of the other. Standard parlay math assumes legs are independent; correlation breaks that assumption.
The short answer
If a star quarterback plays well, his team's chances of covering the spread and his passing-yards over both improve. Those legs are positively correlated — they tend to win or lose together. A negative correlation is the opposite: one leg winning makes the other less likely.
Why it matters for parlays
Multiplying leg probabilities assumes independence. With positive correlation, the true combined probability can be higher than the product suggests; with negative correlation, lower. Sportsbooks price same-game parlays with their own correlation models and extra margin, which is why their payouts on correlated tickets are usually shorter than naive math would suggest.
How EVScout handles it
EVScout detects certain forms of correlation — same-game legs and related markets — and flags them. It does not fabricate correlation coefficients or pretend to fully quantify the combined relationship. When material correlation is detected, the result is labeled with reduced confidence, and when the relationship is unquantifiable, the grade is withheld rather than guessed. The full rules are on the methodology page.
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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