I’m not exactly sifting through piles of job offers, but I know what would be the first thing I’d do if I became a Premiership manager. Apart from politely declining a post-match drink with Sir Alex Ferguson, of course. I would try to reduce home advantage when my team played away.

There are basically three things that decide the outcome of football matches — the class of your side, a little luck and home advantage. It’s difficult to do much about the class of your side without money or time, and preferably both. You can’t control your luck. Which leaves home advantage.

The impact of home advantage on a Premiership match is huge. Adjusting for the quality of the opposition, for every goal that a team score at an away ground they score 1.46 at home. This is on the high side internationally (the figure is 1.39 in Spain, for instance, and the overall basic average is 1.32).

This is, if you think about it, surprising. The impact of class is easy to understand, but why exactly is there home advantage? Why, in a competitive division, haven’t clubs found a way to reduce it.

Dr Henry Stott and Dr Ian Graham have been looking at home advantage and trying to discover its source.

Home teams shoot more, get more shots on target and score more goals. But the figures are (forgive the pun) striking. The improvement shown by a side when at home in getting a particular shot on target is minuscule. So is the improvement in the percentage of shots on target that results in a goal. But the number of shots is massively greater at home than away — a full 27 per cent more.

The away side are also penalised more, with more cards and more penalties. It is not clear (we’ll be working on this) whether this is just the result of away teams defending more or whether there is referee bias.

The next thing the statisticians did was to break down home games into different categories. Our aim was to test certain popular theories about home advantage.

Does it, for instance, vary from one competition to another? A little, it seems. The Champions League, for example, has an average home advantage of 1.44, the FA Cup 1.35 (meaning that 1.35 goals would be scored at home by a team that would score one goal in an away game against such opponents).

We then looked at stadiums to judge the role of the crowd. Stadium capacity makes no impact really and, rather more surprisingly, neither does the size of the crowd. What does matter (a bit) is fullness — the attendance divided by the capacity. A full stadium increases your home advantage by 0.07 of a goal (per away goal you would have scored against that team).

We also looked at the distance travelled. Visiting teams a long way from home is hard, it seems. If the visiting side come from more than 200 kilometres away, add 0.04 to the advantage. But if it’s a derby game that takes a chunk out of the advantage — a full 0.08.

So you can see that a number of the most commonly touted causes of home advantage do matter, but not as much as you may think. From the work we have done it seems that home advantage resides in sides defending more when they are away.

But if they know this, why do they do it? I don’t understand.