  In many sports, it is commonly believed that the home team has an advantage
over the visiting team, known as the home field advantage. Yet its causal
effect on team performance is largely unknown. In this paper, we propose a
novel causal inference approach to study the causal effect of home field
advantage in English Premier League. We develop a hierarchical causal model and
show that both league level and team level causal effects are identifiable and
can be conveniently estimated. We further develop an inference procedure for
the proposed estimators and demonstrate its excellent numerical performance via
simulation studies. We implement our method on the 2020-21 English Premier
League data and assess the causal effect of home advantage on eleven summary
statistics that measure the offensive and defensive performance and referee
bias. We find that the home field advantage resides more heavily in offensive
statistics than it does in defensive or referee statistics. We also find
evidence that teams that had lower rankings retain a higher home field
advantage.
