A home advantage in offside decisions in German professional football (soccer)

Football teams perform more successfully when playing at home than when playing away. A possible cause for this home advantage is that spectators bias referee decisions in favor of the home team. This study is the first to investigate a possible home advantage in offside decisions in football. Therefore, we analyzed archival data from 1,836 matches from the German Bundesliga. We observed a home advantage in offside decisions when the effects of team dominance on the number of offside decisions were removed by calculating an offside score. The presence or absence of the video-assistant referee (VAR) did not affect the home advantage in offside decisions. Moreover, the home advantage in offside decisions occurred only in the presence of spectators and increased with their number. In summary, our study provides first evidence for a home advantage in offside decisions of professional referees, which might be related to spectator presence or behavior.