During the Premier League match between Aston Villa and Fulham on April 5, Lewis Holtby had a shot which was cleared off the line and adjudicated on by the goal line technology used by the league. Plenty of opinions were available on Twitter in the aftermath of this incident as it was so tight but none focused on the most important aspect, namely how accurate is the system?
Firstly, take a look at Lewis Holtby’s shot, which can be found at around the 3:30 mark on the video below.
The suggestion from Keys is therefore that his own eyes are better at identifying whether a goal had been scored than the Hawkeye technology used by the Premier League. In order to assess this, we need to know two things; the error margin of the Hawkeye system and the error margin of Keys’ eyes in these situations. Hawkeye seems to claim 5mm but I have been unable to find an independent assessment, only claims from Hawkeye themselves. As for Richard Keys’ eyes, we will have to make do with the human eye and I am hoping that readers might be able to point me in the right direction on this as a quick google search hasn’t provided me with an answer.
Soon after Keys’ tweet came another from Sporting Intelligence’s Nick Harris:
The problem here is that it is presented as if Hawkeye is 100% correct which we know is not the case given the company’s own literature on its accuracy. The image which ‘proves’ it isn’t a goal is a computer generated image from the Hawkeye system but how accurate is that system? If the ball was over the line by less than 5mm, the system could be wrong if the company’s own claim of a 5mm error margin is correct.
The two media opinions on Hawkeye’s decision, and others like them from twitter are surprising in the main because they either put 100% faith in the human eye or 100% faith in the technology. Both though have error margins and in the end, the choice of goal line technology above anything else should be made on one simple test – is the system being used better than all of the other alternatives?