Officials award marginal decisions to the home side, and do so more where the crowd is larger and closer.
Studies of added time, penalties and marginal fouls find home-favouring patterns that track crowd size and stadium layout, including natural experiments where matches were played without spectators or behind athletics tracks. It is the best-supported single mechanism behind home advantage, and it does not require any official to be aware of it.
In practice
- Added time is longer when the home side is behind and shorter when it leads, by a margin visible across a season.
- A panel that meets in one party's offices decides marginal points in that party's favour without anyone intending it.