Markets
Correlation
Two legs are positively correlated when one winning makes the other more likely. A team covering a large spread and the game going over are correlated, because blowouts usually involve one offence scoring freely.
Correlation is the only mathematically sound reason to parlay. If two legs are genuinely linked and the book prices them as independent, the combined bet is worth more than its parts. If they are negatively correlated — a team winning big and its opponent's receiver going over — the parlay is worth less.
WeBall's engine carries measured coefficients for common pairings, such as team win and team cover, which correlate around 0.78 in the NFL and 0.81 in the NBA.
Want the full version? Read the in-depth guide, with worked examples and the math.
See also
- Same-game parlay — A parlay whose legs all come from one game, priced to account for how they relate to each other.
- Parlay — A single bet combining several selections, all of which must win to pay out.