Graphic: come on ref! How officials' decisions are affected by crowd noise

Sir Bobby Charlton genuinely believes that the crowd helps the players to victory. In advance of tomorrow’s Carling Cup final, the Manchester United legend has called the crowd a twelfth man.

I have always secretly been embarrassed that I use the word “we” when Chelsea, my team, win. But now that Charlton is on the case, all my diffidence has gone. Well done for sticking that one away the other night, Didier, but I did the hard part.

Fans certainly buy into the idea that they are the twelfth man. So much of their identity is wrapped up in their team that a study shows that after a game the victorious fans have higher testosterone levels.

Manager sales - coming to a store near you

Which pitchside workstation would Jose Mourinho plump for from the Acme Dugouts catalogue, 2009

60-second interview: Chris Foy

The Carling Cup final referee on his build-up to the big day and why he hopes he is not the centre of attention at Wembley

• 60-second interview: Jay DeMerit

• 60-second interview: Simon Jordan

• 60-second interview: Peter Ridsdale

Related Links

• Split decision on 'Quite Big Phil'

• Applying a new watching brief to football

• There are no cracks in Benitez's master plan

But Charlton and fan folklore aside, is it true? At the Carling Cup final contested by United and Tottenham Hotspur tomorrow, Carling and Sky Sports are going to be recording crowd noise and seeing which set of fans shouts the louder. I wish they were doing this at games every week. As I will show, it would be great to have a proper data series of crowd noise.

Let’s start with this. Crowd noise does make a difference. We know this because a fabulous academic paper recorded referees’ responses when watching a televised match with the sound off and contrasting that with the response of a group watching with the sound on.

The noise of the crowd led referees to give fewer free kicks against the home team and to penalise the away team more often than when the sound was off. Significantly fewer incidents were judged to be infractions without the crowd noise to prompt the officials.

The second indication that crowd noise works is given by home advantage. Fink Tank work — simulations by Drs Henry Stott, Ian Graham and Mark Latham — over the past few years indicates that home advantage does not lie in familiarity with a stadium (indeed, our latest work suggests that teams actually do better for a period when they move to a new stadium, although this is not statistically significant).

The impact lies somewhere in the balance of the crowd in the stadium. There is one additional factor. We found a strong and significant impact made by the distance a team have to travel to a game. The farther the away team have to travel, the greater the damage to their performance when they get there.

And then there is the third hint that the crowd is genuinely the twelfth man. Home advantage appears to belong to the team rather than the individual.

When a striker is in front of the net, they are no more likely to turn a shot on target into a goal when at home than they are away. But home teams still score more. Why? Because they shoot on the target more. So while individuals show the same finesse wherever they play, the team with the crowd behind them tend to pour forward.

Unfortunately, at that point the hints stop and the mystery begins. The size of the crowd and the capacity of the stadium are not significantly related to results. In an earlier study, the fullness of the stadium was (just) statistically significant and positively related to home advantage, but adding a bit more data in this latest work, we find that it (just) is not statistically significant.

So, Carling and Sky, we need your data on noise if we are going to know more. Very good that you are measuring tomorrow. But you can’t stop now.