A decade of violence and empty stadiums in Egypt: when does emotion from the terraces affect behaviour on the pitch?

In less than a decade, the Egyptian Premier League has experienced three distinct changes between periods of competition in either crowded or empty stadiums. We exploit this unique sequence of natural experiments, to answer two questions neglected by the still emerging literature on the effects of crowds on behaviour and decision making. First, does reinstating a supportive crowd after a long period of absence affect performances on the pitch? Second, is any reduced home advantage from competing in empty stadiums robust to repeating such an experiment? We find that eliminating crowds decreased or even reversed home advantage after an incident of extreme crowd violence in 2012, but there were no significant effects when crowds were reinstated in 2018 and once more excluded in 2020.