Study – ARs make too many inaccurate offside decisions!

As some of you may know, in the last week’s Premier League game between Manchester United and Queens Park Rangers, the assistant referee missed an obvious offside by a proverbial mile. Compounding the mistake, the referee pointed to the spot and sent off the QPR defender for fouling Ashley Young inside the area and denying him an obvious goal scoring opportunity.  Needlessly to say, neither the foul (however it might have been debatable) nor the send off would occur if the assistant referee correctly signaled for the offside.

The assistant referee’s mistake got us thinking: how prevalent are assistant referees’ offside mistakes during any given game? Is it common not?  Well, thankfully, we were not the first ones to ask this question and found out that there were several studies conducted to answer precisely the same question.

According to one study that looked at assistant referees’ performance during the FIFA World Cup 2002 and 2006, there was an error percentage of approximately 26% and 7.6%, respectively.  Interestingly, the significantly lower error rate of 7.6% for the FIFA World Cup 2006 might be attributable to overly restrictive definition of what constituted an inaccurate call.  The study counted as an error those decisions where the attacker was either 2 meters in front or behind the second-last defender.  Presumably, anything in between was too close to call and was not counted as a bad call.  In another study, published in Journal of Sports Sciences in March 2010, it was reported that assistant referees were accurate in their offside decision-making 82.5% of the time. That means that 17.5% of decisions were incorrect.  Moreover, a study of the highest Dutch football league in 2005 revealed an error rate of approximately 20%.  Finally, in a study looking at the performance of Belgian and FIFA assistant referees using computer animations, it was determined that FIFA assistant referees were 72.9% accurate or 27.1% inaccurate and that their Belgian counterparts were 63.2% accurate or 36.8% inaccurate.

These 20% error rates seem a bit high to us.  Mistakes do happen and they are part of the game.  But these 20% error rates just do not conform to our own personal experiences.  Let us know what you think.  Are assistant referees making these many mistakes?


P. Catteeuw, B. Gilis, J. Wagemans, W. Helsen, Offside decision making of assistant referees in the English Premier League: Impact of physical and perceptual-cognitive factors on match performance, Journal of Sports Sciences (March 2010).

C. Helsen, W. Starkes, J. Westen, M. Macmahon, Decision-making skills and deliberate practice in elite association football referees, Journal of Sports Sciences (January 2007).

P. Catteeuw, B. Gilis, J. Garcia-Aranda, F. Treasaco, J. Wagemans, W. Helsen, Offside decision making in the 2002 and 2006 World Cups, Journal of Sports Sciences (August 2010).

P. Catteeuw, B. Gilis, W. Helsen, Offside decision-making process in association football using recall paradigm, Jourbal of Sports Science and Medicine (2007).

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