They didn’t know what they got till the crowd was gone
研究了荷兰顶级足球联赛五个赛季的数据，发现疫情导致的空场使主场优势完全消失，主队进球减少，客队黄牌减少，且裁判决策并非中介因素。
This paper revisits the relationship between Covid-19-related full and partial absence of stadium attendance and match outcomes, analyzing five seasons of the top tier of professional football in the Netherlands. Empty stadiums caused home advantages to disappear completely due to home teams scoring fewer goals. Additionally, in empty stadiums, away teams received fewer yellow cards. This persisted even when stadiums were filled to a maximum of one-third of their capacity. Under these circumstances, there were no effects on team performance. Thus, it is improbable that referee decisions were the intermediary factor influencing team performance. Players of home teams appear to have been directly and adversely affected by the absence of stadium crowds. • The effects of empty football stadiums in the Netherlands are analyzed. • The lack of crowd support had a negative effect on home team performance. • Home advantages in match outcomes disappeared. • Away teams received fewer yellow cards. • Match outcomes were not affected by biased referee decisions.