How does the crowd affect home field advantage? Evidence from COVID affected seasons in the Top 5 European soccer leagues

Using data from Football Reference and FiveThirtyEight from 2015 through the 2021 season, I use a stadium fixed-effects model to better understand crowds' effect on goal differential (a proxy for match outcome). Similarly, I use a three-way fixed effects model on stadium, season, and referee to test the crowd's effect on the referee. With an extra season of data (previous research only used until the 2020 season), I found that fans are worth 0.23 more home goals than away goals across all leagues.

I also found that fans were worth 0.46 more yellow cards in favor of the home team, and the other referee outcomes follow this trend. However, in both cases, league-specific results vary. The results support the hypothesis that fans influence match outcome and refereeing, though any conclusion must be tempered with the disclaimer that COVID changed many factors in addition to the absence of fans.