Referee–team relationships and yellow cards in football

There is a wide consensus among football observers and sports economists that referees appear to be systematically biased toward the home team (Courneya & Carron 1992; Nevill & Holder 1999; Pollard & Pollard 2005). This may be due to a variety of factors that implicitly point to the existence of long-term relationships between referees and teams.

Among the already recognised factors, referee and team characteristics – such as a referee’s age, and experience or a team’s prestige or players’ ethnicity and veteran status – play an important role (Page & Page 2010; Reilly & Witt 2011; Gallo et al. 2013). These factors have been found to affect referees’ treatment of particular teams and players. Characteristics that players and referees have in common, such as race or nationality, also appear to be of importance (Dawson & Dobson 2010). In addition, referees have different exposure to different teams, which may affect their treatment of individual teams. If older and more experienced referees have developed deeper relationships with teams whose home matches they referee, their biasedness could be explained through long-term relationships. Furthermore, differences in exposure may also come from the tendency of referees to minimise their travel time to matches. Because some referees may have the ability to choose matches, by accepting or rejecting assignments, home bias may be a by-product of referees’ self-selection to home teams with whom they inadvertently already have relationships.

Finally, home bias appears to grow in matches where the home team has a distinct motivation to perform well. The level of rivalry between teams, match intensity, and the significance of a match to league rankings can affect the advantage that the home team receives (Neave & Wolfson 2003; Witt 2005; Dawson et al. 2007).

Since the interaction between referees and teams is not limited to a single match, their past and future expected interaction may inadvertently affect referees’ objectives and decisions. Besides striving to achieve fairness of refereeing during matches and being accepted by fans to a certain extent (Garicano et al. 2001), referees may also strive to keep equitable running tabs of calls across matches, or sustain positive long-term relationships with teams to receive ‘warm glows’ from these relationships. If this conjecture holds, some of the identified drivers of referees’ favouritism may stem from time-constant or dynamic bonds between referees and the teams they oversee.

In our recent study, we put data on the English football leagues to the test, evaluating a number of hypotheses about the existence of long-term referee-team relationships and their bearing on refereeing calls (Hlasny & Kolaric 2013). Our data consists of 27,449 matches for 11,055 referee-team relationships over 13 seasons. These relationships were for 210 referees and 137 teams in four English leagues.

The count of yellow cards (and alternatively red cards and penalties) given to respective teams was linked to several measures of referees’ up-to-date and expected long-term bonds with the teams. In particular, we evaluated three hypotheses related to the relationship theory:

  1. Geographic proximity and the extent of referee-team interaction have a positive effect on the advantage that a referee confers on a team.
  2. The referee confers the greatest advantage to a team when the match is intensive, particularly when the referee-team bond is strong.
  3. Changes in the team’s stake in winning (e.g. pending relegation or promotion) increase the bias toward the team, particularly when the referee-team bond is strong.

The findings of this paper show that:

  • The geographical distance between a referee’s home town and the stadiums of the respective teams have a significant impact on the disciplinary cautions issued during a match. In terms of yellow cards, referees over the age of thirty give a higher home advantage than younger referees, by 0.2 cards per match. For teams, their up-to-date as well as future expected count of matches is associated positively with the home advantage they receive in terms of yellow cards. Similarly, the count of matches that teams ever play under specific referees is associated positively with home advantage.
  • A referee’s perception of distances – or their effect on disciplinary cautions – changes over his life time as he develops different relationships with the two respective teams. In fact, a referee’s home town tends to be significantly closer to the home-team stadium (average distance 153km) than to the away-team stadium (194km). Also, referees with more than eight years of experience travel fifteen kilometers less than their junior colleagues.
  • Additionally, the analysis also gives consistent support to the hypothesis that the relative stake a team has in a match, compared to its opponent, affects positively the advantage it receives from a referee. This effect increases in magnitude with the relative strength of the referee’s bond with that team.
  • The intensity of a match – in terms of probability of a draw or close half-time scores – also appears to affect home bias, and the strength of this effect depends on the bond between referees and teams. These trends extend over time and across league divisions.

These results suggest that the findings in previous literature may in part be due to the existence of an implicit bond between referees and teams, and should be interpreted with that in mind. Our results do not invalidate previous findings, but merely point to one mechanism through which the effects of home vs. visitor team identity, referee age and tenure, and team professionalism operate. One implication is that regardless of teams’ and referees’ characteristics and home-crowd effects, referee bias may simply develop through geographic proximity or exposure to specific teams.

Authors’ note: This article is based on our recent paper – Hlasny, V., & Kolaric, S. (2013). Catch Me If You Can: Referee-Team Relationships and Disciplinary Cautions in Football.