Referee Bias in Football : Actual vs Expected Additional Time

I introduce a new variable, ball-in-play time, to investigate whether referees in football tend to favour home teams while deciding on additional time under social pressure. Hence, any systematic difference between actual and expected additional time can be considered as `bias'. I exploit the games played behind closed doors during Covid-19 and find that referees favour home teams only when fans are present. This is evidence of the effect of social pressure on referee decisions. After detecting referee bias arising from social pressure, I examine the post-Covid-19 era to test if the nudge theory applies and referees benefit from the situation and begin deciding impartially. However, referees continue favouring home teams when fans back to stadiums