What happens when football meets technology? The inclusion of Video Assistance Referee with heterogeneous treatment time.

Abstract

Video Assistance Referee (VAR) is one of the major changes in football in the modern time. This paper addresses whether VAR affected several dimensions of the game, reducing the bias that referees may have in favor to home and rich teams. Exploiting the timing differences in the implementation of VAR in six European leagues, this paper investigates whether it affected the number of penalties, red cards, yellow cards, and goals of teams, in absolute and relative terms (or bias). The results show that VAR reduces the bias between poor and rich teams when poor teams are visitors, although there is no reduction in bias when poor teams are hosts. For variables in absolute terms the effect is no clear. The effects of VAR are heterogeneous across leagues, being the Premier League the one that suffered more changes after implementing the policy.