Football is returning! People are divided in the UK about whether that’s a good thing or not, but the Bundesliga in Germany will start again on Saturday (we’ll make forecasts tomorrow and here’s our end-of-season forecasts).
But it’s going to return without spectators – or “behind closed doors”, in the football vernacular. Will that affect anything at all?
Regardless of what we might think, we Scorecasting Economists like to look at the numbers to answer questions like this. They’re interesting from a sporting perspective, but also more broadly. Economists care about outcomes, and care about distortions in outcomes away from what we might think of as their natural level. They care about undue influences on outcomes, discrimination in decisions, and other external events that might affect how things turn out.
Football yields great opportunities to investigate things like this. Why do home teams win really often? Economists have proposed that it’s the referee that are actually the mechanism through which fans help the home team to win. So if fans aren’t present, they can’t influence outcomes via the referee. We’ve started to investigate this.
How many matches have taken place behind closed doors historically? It turns out, a small number – about 0.1% of all matches played across England, Italy, Spain, France and Italy, as well as the Europa League and Champions League. That’s 192 matches 131,229. It’s not many, but we can reduce that sample down a little, since there’s no point looking yet at Germany or England, since there have been no closed door matches ever in these two country (until now).
We focus on the matches in the plot below:
What differs between them? In the following two charts, we look simply at the difference in mean outcome between “normal” matches, and “closed-door” matches:
Home teams score fewer goals, and win fewer matches. Referees award away teams almost half a yellow card less. More shots on target are saved. Less injury time is awarded, though this effect is insignificant.
Hence this points towards home advantage being removed by playing without spectators. And it suggests the mechanism may be referee related, since the strongest effect by some distance is the yellow card effect, which is robust to all sorts of controls.
Many of the effects are insignificant. This could be because they are insignificant. But it could be because we have a small sample of closed-door matches. Hence while the general public is highly ambivalent about football’s return, as scholars we are delighted that we will soon have a lot more closed door matches to use in this work. We’ll be updating in the coming weeks…