Is crowd support important in professional football’s home advantage? A systematic review based on covid-19 effect

The COVID-19 pandemic enabled a natural experiment examining how spectator absence impacted home advantage in football. This systematic review analysed research characterizing home advantage dynamics with no fans present across diverse leagues worldwide. The aim was assessing the profile, trends, methodologies, procedures, and developments in this emerging field. Searches in specialized databases identified 50 relevant studies following PRISMA guidelines. These works were systematically assessed to extract key details related to design, country, competition level, analytic approach, performance variables, and home advantage findings. Overall methodological quality was categorized as excellent. Most research occurred in top European men's leagues, with limited attention to other levels. Predictive (58%) and descriptive (36%) investigations predominated, chiefly utilizing regression and group comparisons. Points, goals, cards, and result were the primary metrics. Results demonstrated home advantage decreases without spectators in most leagues, conforming to social facilitation theories stipulating performance declines minus audience encouragement. Additional research is warranted across female competitions, youth categories, amateur settings, and knockout tournament stages. Maintaining methodological rigor while expanding domains will solidify understanding of this intricate phenomenon to guide teams performing both home and away.