Researchers cast doubts over Wimbledon Hawk-Eye aid branded a nonsense by Federer

Hawk-Eye, and similar tools which are used to supplement or replace decision-making by umpires and referees, are becoming increasingly common in televised sports coverage.  

But the technology has split opinion in the world of tennis. Wimbledon champion Roger Federer has described Hawk-Eye as "nonsense" while Andy Roddick, a former finalist in the tournament, is a big fan of the system.  

Split decision: Researchers have doubts about the accuracy of Hawk-Eye technology

Now researchers at Cardiff University's School of Social Science have challenged whether the Hawk-Eye can always be right.  

In a paper entitled You cannot be serious! Public Understanding of Technology with special reference to Hawk-Eye, the researchers claim errors made by the machine can be greater than 3.6 millimetres - the average error stated by its makers.  

The paper says the International Tennis Federation, which tests the machines for use, would accept Hawk-Eye had passed its test if it called the ball 'in' by 1mm, while the true position was 'out' by 5mm.  

Led by Professor Harry Collins and Dr Robert Evans, the team argues such devices could cause viewers to overestimate the ability of technological devices to resolve disagreement among humans.  

Professor Collins said: "We used Hawk-Eye as the principal illustrative example as it is the most well-known of the commercial systems and is currently being used to make decisions in major tennis competitions such as Wimbledon.  

"Technologies such as Hawk-Eye are meant to relegate line-call controversies to the past. However, our analysis has shown that Hawk-Eye does not always get it right and should not be relied on as the definitive decision maker."  

Sceptical: Roger Federer is no fan of Hawk-Eye

The paper states such systems should not correct but should reproduce human systematic errors - the typical errors made by human judges and viewers such as calling a tennis ball out when it looks out to everyone, even if the electronics suggest it might just have been in.  

At the same time, the paper says, the devices should be used as they are now to correct or reduce human random errors which come from lapses of concentration, an obscured view or very fast action. But the researchers say the fact the machine can make mistakes should always be clear.  

Professor Collins said: "To avoid any chance of misleading the public, we believe that Hawk-Eye's conclusion should be accompanied by statements and/or displays of the size of the possible errors, as is normal in science.  

"This would ensure that the public is much better informed as to the limits and possibilities of technology." 

The analysis also concludes Hawk-Eye might be in danger of changing the traditional nature of certain games because it does not take account of traditional areas of human systematic error when making judgements.  

Such errors include criket umpires giving the benefit of the doubt to batters in the case of leg before wicket or judging tennis balls to be out when skidding gives the appearance of their being out even if they have just clipped the line.  

The paper is due to be published in the journal Public Understanding of Science next month.