Europe South Asia Asia Pacific Americas Middle East Africa BBC Homepage World Service Education
BBC Homepagelow graphics version | feedback | help
BBC News Online
 You are in: Sci/Tech
Front Page 
UK Politics 
Talking Point 
In Depth 

Jim Giles, Science Museum
When the players are close to the assistant referee, the attacker benefits
 real 28k

Thursday, 2 March, 2000, 11:20 GMT
Offside rule 'impossible to call'
Fast players make close calls tough
Fast players make close calls tough
By BBC Science's Suzanne Mooney

Assistant referees get nearly 10% of offside decisions wrong because they are not standing in the right place, scientists say.

However, the research team which showed this believe it is not always the officials' fault, but is "inevitable" because of the "limitations" of human eyes.

Offside decisions can decide matches
Offside decisions can decide matches
Making an offside decision is in theory an easy task for assistant referees - otherwise known as linesmen or women. An attacker either has two opposition players between them and the goal line the when the ball is passed, or does not.

But mistakes are frequent and players and fans hotly dispute what they see as wrong judgements - debates that can rage for years.

Critical angle

Until now, the blame has been loaded on the shoulders of the assistant referee, who stands at the side of the pitch.

But a report published in the journal Nature shows that in-built human error will always remain, and that no assistant referee can keep up with the speed of today's fast-moving game.

The research was led by Dr Raoul Oudejans at Vrije University in the Netherlands. It shows that the position of the assistant referee in relation to play is key to making the right call.

They ran experiments at live games using head mounted cameras and also video footage of 200 European league and World Cup games.

Jim Giles, of the Science Museum in London, has followed the work and explained: "For the assistant referee to make an accurate decision, he or she needs to be level with the last defender.

"Now what this study has shown, is that the assistant referees tend to stand about a metre nearer the goal than the last defender, and this is why they make these mistakes."

This means that the official's line of sight favours the attacker, if the attacker runs between the defender and the official and vice versa.

By standing in the correct position, assistants could minimise their mistakes. But players like Michael Owen of Liverpool and Claudio Lopez of Valencia run almost as fast as an Olympic sprinter. It would therefore need an assistant with equivalent athletic ability just to keep up.

Video evidence

Nonetheless, the wrong decision in an important match could cost a football club millions of pounds, which is why many are now calling for video replays to be used in making line calls.

This technology is used in other sports, but some argue that it would slow the football down too much.

This is not the first time offside decisions have been subjected to scientific scrutiny. Research in Spain in 1998 suggested that errors were made because assistant referees physically could not move their eyes fast enough to take in all the action.

To make a correct decision, the official has to assess the positions of the passer, receiver and last defender all at the same time, but they could be 40 metres apart.

Search BBC News Online

Advanced search options
Launch console
See also:

27 Dec 98 |  FA Carling Premiership
Gregory demands video evidence
17 Jan 00 |  Sci/Tech
Electronic eye for blind man
11 Oct 99 |  Sci/Tech
Looking through cats' eyes
Internet links:

The BBC is not responsible for the content of external internet sites

Links to other Sci/Tech stories are at the foot of the page.

E-mail this story to a friend

Links to more Sci/Tech stories