With EURO2021, football lovers around the world rejoice at the chance of watching one of the very first international sports competitions since the pandemic started. For fans, it’s an enthralling competition, especially as the end outcome is almost always unpredictable.

A team of researchers focused exactly on that: the purely random events that lead to goal scoring in football. According to their research every other goal (46%) has some random influence on it.

Football is a weird game. Unlike most other team sports, where plenty of points are scored, football games typically have 2-3 goals — and each of them is a very big deal. Unlike basketball or handball, where a shot going in versus narrowly missing is unlikely to decide the end result of the game, football is often decided by this type of detail. Watch enough football games, and you’ll be stuck with the feeling that sometimes, games are decided not by who is the better team, but rather by a bit of luck.

Dr. Daniel Memmert, Executive Head of the Institute of Exercise Training and Sports Informatics at the German Sport University Cologne, wanted to focus on that. Along with his colleagues, Memmert analyzed 7,263 goals scored in the English Premier League in seven years, starting with the 2012/13 seasons. Since the English Premier League is arguably the best football league in the world, it seems like a good place to start.

The researchers’ analysis selected six variables that defined the randomness involved in scoring a goal: goals following a rebound, long-range shots, deflected shots or goals created by defensive errors like, for instance, own goals. The study also included nine situational variables such as season, matchday, match location, match situation, goal number or team strength.

The researchers were surprised to see that 46% of all scored goals had some form of random influence to them. Furthermore, more than 60% of all matches ended either in a draw or with a goal difference of one goal — emphasizing the importance of these chance goals.

“A single random goal can therefore be enough to significantly change the outcome of a match. Thus, chance is not only highly relevant in the case of that particular goal. Chance also plays a significant role in deciding the final score of the match,” explains Memmert.

Interestingly, the prevalence of these chance goals appears to be dropping in recent seasons. Sport scientist Fabian Wunderlich, first author of the recently published paper explains:

“The results clearly highlight the essential role of chance in football, as almost every second goal benefits from random influence.”

“Another interesting finding is that the proportion of chance goals has dropped from 50% to 44% over the last seven seasons. This might be caused by the fact that match preparation is becoming increasingly professional and data-driven, or that players are becoming better trained technically as well as tactically.”

The occurrence of chance goals also appears to be dependent on the match situations. Some specific situations (like free kicks or corner kicks) tend to lead to more random influence in scoring goals, which suggests that coaches should better prepare for this type of situation. In fact, they likely already are: the influence of randomness goals is much higher for weaker teams, which suggests that consciously or not, teams may already be playing to these odds. The likelihood of chance goals was also higher when the score was a draw.

The team encourages other researchers to further look at the data, at other types of leagues and games, and on women’s football as well, to see if “randomness in goal scoring is a relatively stable inherent characteristic of football or highly dependent on the circumstances of the play.”

“Moreover, further research should tackle the question whether physical, technical, tactical and psychological changes over the last years were responsible for the decreasing influence of randomness on goal scoring,” the study adds.

As football (and sports in general) becomes more and more influenced by this type of data, we can expect studies like this to make an impact on how managers and teams approach the game. For better or for worse though, football remains an unpredictable game, with a lot of randomness involved.

The study was published in the Journal of Sports Science.