“…Addressing team and referee heterogeneity, we found average effects of playing behind closed doors in the 2019/20 season that were consistent with the aforementioned pre-Covid-19 estimates, which had relied on much smaller samples of matches: no significant general impacts on match outcomes or score lines, but fewer yellow cards awarded to away teams (Bryson et al, 2021). There have been several other studies of these patterns since Covid-19, either using sub-samples of our data (e.g., Endrich and Gesche, 2020) or alternative empirical approaches (e.g., Benz and Lopez, 2020;Scoppa, 2021), finding similar results (see the summary in .…”