An
article in today's Huffington Post by Raj Persaud and Adrian Furnham
talks about the scientific evidence that supports the idea of referee
bias in football. One of the studies they describe is the recent work by Anthony Constantinou, Norman Fenton and Liam Pollock** which developed a
causal Bayesian network model to determine referee bias and applied it
to the data from all matches played in the 2011-12 Premier League
season. Here is what they say about our study:
Another recent study might just have scientifically confirmed this
possible 'Ferguson Factor', entitled, 'Bayesian networks for unbiased
assessment of referee bias in Association Football'.
The term 'Bayesian networks', refers to a particular statistical
technique deployed in this research, which mathematically analysed
referee bias with respect to fouls and penalty kicks awarded during the
2011-12 English Premier League season.
The authors of the study, Anthony Constantinou, Norman Fenton and Liam
Pollock found fairly strong referee bias, based on penalty kicks
awarded, in favour of certain teams when playing at home.
Specifically, the two teams (Manchester City and Manchester United) who
finished first and second in the league, appear to have benefited from
bias that cannot be explained by other factors. For example a team may
be awarded more penalties simply because it's more attacking, not just
because referees are biased in its favour.
The authors from Queen Mary University of London, argue that if
the home team is more in control of the ball, then, compared to
opponents, it's bound to be awarded more penalties, with less yellow and
red cards, compared to opponents. Greater possession leads any team
being on the receiving end of more tackles. A higher proportion of these
tackles are bound to be committed nearer to the opponent's goal, as
greater possession also usually results in territorial advantage.
However, this study, published in the academic journal 'Psychology of
Sport and Exercise', found, even allowing for these other possible
factors, Manchester United with 9 penalties awarded during that season,
was ranked 1st in positive referee bias, while Manchester City with 8
penalties awarded is ranked 2nd. In other words it looks like certain
teams (most specifically Manchester United) benefited from referee bias
in their favour during Home games, which cannot be explained by any
other possible element of 'Home Advantage'.
What makes this result particularly interesting, the authors argue, is
that for most of the season, these were the only two teams fighting for
the English Premiere League title. Were referees influenced by this, and
it impacted on their decision-making?
Conversely the study found Arsenal, a team of similar popularity and
wealth, and who finished third, benefited least of all 20 teams from
referee bias at home, with respect to penalty kicks awarded. With the
second largest average attendance as well as the second largest average
crowd density, Arsenal were still ranked last in terms of referee bias
favouring them for penalties awarded.
In other words, Arsenal didn't seem to benefit much at all from the kind
of referee bias that other teams were gaining from 'Home Advantage'.
Psychologists might argue that temperament-wise, Sir Alex Ferguson and
Arsene Wenger appear at opposite poles of the spectrum.
** Constantinou, A. C.,
Fenton, N. E., & Pollock, L. (2014). "Bayesian networks for unbiased
assessment of referee bias in Association Football". To appear in
Psychology of Sport & Exercise. A pre-publication draft can be found
here.
Our related work on using Bayesian networks to predict football results is discussed
here.
