Methodology & sources
Data
Play-by-play, game results, betting lines and officials from nflverse (CC-BY 4.0), credited with thanks. Referee for each game comes from nflverse's officials data, falling back to its schedule file.
Counting
We count accepted penalties only. Declined and offsetting penalties are shown separately and excluded from totals. Play-by-play records one penalty per play, so plays with multiple fouls may be undercounted. Spread results use nflverse closing lines; the favorite 'covers' if it wins by more than the spread, pushes excluded. Primetime = kickoff 7 PM ET or later, or any Monday/Thursday game.
Drive interruptions: definitions
Momentum drive: a possession that had already gained 2+ first downs (including first downs by penalty) before the play. Drive interruption: an accepted penalty on the offense during a momentum drive. Per 100: interruptions per 100 drives that reached 2+ first downs. Ended without points: the drive finished without a touchdown or field goal (any result after the flag, e.g. punt, turnover, end of half). 4th-quarter share: share of accepted flags in Q4 or overtime. After a big gain: accepted flag on the next play following a 20+ yard non-penalty gain. Replay reviews: plays nflverse marks as replay or challenge; these are mostly booth- or coach-initiated and shown separately. Penalty yardage, drive results and timing all depend on the teams playing; these numbers describe what happened and say nothing about any official's intent.
Fair use of these numbers
Penalties are called by a 7-person crew, not the referee alone, and depend heavily on the teams playing. Every figure is shown with its sample size and league average. Samples under 15 games are flagged. We describe numbers neutrally ('above/below average') and make no claim about any official's intent, bias or integrity.
Corrections
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