Are Home Teams Favoured by Referees in Football/Soccer?

An analysis investigates whether football referees are biased towards home teams by examining data on fouls and yellow cards. The study uses cards per foul as the primary metric to control for varying team playstyles and foul rates. To isolate potential referee bias, the author accounts for team strength using a "territorial dominance" index derived from shots and corners. The analysis also plans to leverage the natural experiment of games played in empty stadiums during the COVID-19 pandemic to measure the impact of crowd pressure. Initial exploration reveals that home teams consistently receive fewer yellow cards across all leagues, setting the stage for a deeper statistical investigation.