VAR is not precise enough to give accurate offside decisions in football, study claims 

Almost three years since its introduction to the Premier League, video assistant referee (VAR) is still dividing opinion among football fans.

The state-of-the-art video technology has won plaudits from some but has also experienced its fair share of disasters along the way, with the debate about its effectiveness and whether it slows down the speed of the game still raging on.

Now a new study has waded in, and it’s not exactly a ringing endorsement.

Researchers suggest that VAR is currently not precise enough to give accurate offside decisions in football, in part because of how humans observe the data. 

Dr Pooya Soltani, who led the study, said: ‘Whilst VAR is useful to spot obvious errors, it shouldn’t be relied upon completely to make referee decisions.’ 

The research will be music to the ears of Match of the Day pundits Gary Lineker and Alan Shearer, both of whom have questioned the technology’s effectiveness in the wake of several controversial decisions. 

Experts carried out an experiment (pictured) and found that, on average, a person watching footage of a pass thought the ball was kicked 132 milliseconds later than it actually was

This is long enough for the players to be in a different location and therefore could potentially change the outcomes of offside, the researchers from the University of Bath said

VAR was introduced to the Premier League in 2019 to review ‘clear and obvious errors’ in four game-changing incidents: goals, penalties, straight red cards and mistaken identity. 

The technology uses film footage from pitch-side cameras, meaning that VAR operators can view the action from different angles and then offer their judgements on incidents to the head referee to make a final decision. 

Critics of VAR further argue that it hampers the flow of the game, however some research suggests it has reduced the number of fouls, offsides and yellow cards.

In the new study, researchers from the University of Bath’s Centre for Analysis of Motion, Entertainment Research and Applications, used optical motion capture systems to assess the accuracy of VAR systems.

Dr Soltani filmed a football player receiving the ball from a teammate, viewed from different camera angles, whilst recording the 3D positions of the ball and players using optical motion capture cameras. 

Participants viewing the clips were then asked to determine the exact moment of the kick and judge whether the ball receiver was in an offside position.

The study found that, on average, the participants thought the ball was kicked 132 milliseconds later than it actually was, as measured by the optical motion cameras. 

It also found that participants were more accurate in their judgements when the action was viewed at 0 and 90° angles, and when VAR guiding lines were present.

The state-of-the-art video technology has won plaudits from some but has also experienced its fair share of disasters along the way, with the debate about its effectiveness and whether it slows down the speed of the game still raging on 

The research will be music to the ears of Match of the Day pundits Gary Lineker and Alan Shearer, both of whom have questioned the technology’s effectiveness in the wake of several controversial decisions

Dr Soltani said: ‘VAR is really useful in helping referees make accurate decisions, but this study has shown it has definite limitations.

‘The frame-rate and resolution of the cameras used in VAR sometimes does not keep pace with the fast movements, meaning that sometimes the player or the ball is blurred.

‘So, the viewer has to use their own judgement to extrapolate where the players were at the moment the ball was kicked, which affects whether it is offside or not.

‘My research found that the ball was kicked 132 milliseconds earlier than the participants perceived, which doesn’t sound like much, but in a fast-paced game it could be long enough for the players to be in a different location and therefore could potentially change the outcomes of offside.’

The study suggests that for marginal offside decisions, thicker guiding lines in the VAR could be used to represent the uncertainty zone.

The accuracy could also be improved by viewing the gameplay from multiple angles, the researchers said.

Dr Soltani added: ‘Using higher resolution, faster frame-rate cameras, and volumetric motion capture approaches would improve the accuracy of VAR, but would be a lot more expensive.

‘Whether right or wrong, I think the referee’s final decision adds flavour to the game.’ 

He presented his findings at the 40th Conference of the International Society of Biomechanics in Sports.