Is Home Advantage Null and Void in the Absence of Fans?
Does the absence of fans render the home team “advantage” obsolete?
The most awaited football match in almost three months, Der Klassiker, Borussia Dortmund hosting Bayern Munich. If the home team won, they would close the gap to Bayern at the top of the Bundesliga to just one point. Dortmund had beaten Bayern in their two most recent meetings at Signal Iduna Park, and had the best home form for any team in the Bundesliga this season, scoring over 3 goals a game. Dortmund would surely run the defending champions close at a ground where they have enjoyed so much success.
During the match itself, Dortmund were limited to a few long-range efforts and a very easy clearance off the line. Bayern ran out comfortable 1–0 winners.
Were the home team missing the extra drive that their famous fans bring them? Would more pressure have been put on the referee to give a penalty for a supposed deliberate handball by Boateng if the vociferous fans were present? Does the absence of fans render the home team “advantage” obsolete? Or are we simply reading too much into this?
The New Normal
At the time of writing, there have been 27 matches played behind closed doors since the resumption of the Bundesliga after the coronavirus outbreak. Only 5 have been won by the home team.
To verify if the away teams were in fact the favourites in these matches, I converted the pre-match odds into win probabilities and arrived at the likelihood of the three possible results (home win, draw and away win) for all the 27 fixtures played in the Bundesliga after the resumption in May.
The following observations can help us conclude that there is a clear trend away from a perceived pre-match home advantage:
1. Of the 17 matches (63%) that were predicted to be home wins, only 5 (19%) ended with this result
2. All of the 5 home wins went as per pre-match odds, there were no surprises
3. 5 of the 12 away victories were not the most likely result as per pre-match odds
This dearth of home victories in the absence of fans is not just peculiar to this season. If we look at the history of all the matches played behind closed doors, we can see that the % of home victories decreases in the absence of fans. Since 2002, there have been over 150 matches without fans in the major European leagues. When comparing the results in these leagues with and without fans, we can see that the win % of home teams falls from 46% to 36% in closed door matches, and the win% of away teams increases from 26% to 34%.
Influence Conformity
In a study published by Ignacio Palacios Huerta, Professor of Management, Economics and Strategy at the London School of Economics, there is evidence that suggests that referees systematically favour home teams. This study points out that referees “shorten close games when the home team is ahead and lengthen close games when the home team is behind”. They do this by adjusting the amount of extra time played at the end of the match. While the average extra-time is 3 minutes, referees tend to adjust this in close contests. The study notes the following:
1) If the home team is behind by 1 goal, the extra time is 35% above average
2) If the home team is ahead by 1 goal, the extra time is 29% below average
3) If the visiting team scores at the end of regulation 90 minutes, extra time went on 15% longer rather than when the home team scored.
4) This deviation from the average extra time was only true if games were close (one-goal margin between the teams)
In another study, 40 qualified referees were made to judge 47 incidents from a match with and without crowd noise. Those watching the footage with noise awarded fewer (15.5%) fouls against the home team. Psychologists refer to this term as “influence conformity”.
Without the bellowing of thousands of spectators behind you, referees do not get influenced as much and it allows for a neutral playing field. The trend of a lower proportion of home victories is here to stay and it will be interesting to see how it impacts different leagues and different sports all over the world.
