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Parcae
Glossary strategy

Key Number

In short: A margin of victory that occurs disproportionately often in a sport, making lines that cross it especially valuable. In NFL, 3 (field goal) and 7 (touchdown) are the primary key numbers.

Key numbers matter because the distribution of game outcomes isn’t smooth. A spread that moves from -2.5 to -3.5 in football crosses the key number 3, which represents a much larger swing in win probability than crossing a non-key number.