Fans are not amused about decisions made by video assistants

The video referee in the spotlight

For their analysis, the team employed "text mining", an algorithm-based analysis process which unearths structures of meaning buried in text data. The study focused on the automatic extraction of tacit knowledge from large amounts of text data, in this case tweets, collected via an interface. 

"We used the official hashtag for each game to ensure that the tweets really refer to the game in question," explained Dr. Kolbinger, elucidating the procedure. “We also, for the first time ever, used a new text classification algorithm. In our case, it performed better than algorithms used in previous studies." 

To avoid so-called overfitting – the over-adaptation of a model to a given data set – the team allowed only a fraction of the variables to flow into each individual step during model fitting. 

In its data analysis, the team examined whether tweets referring to a specific VAR situation are formulated positively or negatively. They found that the average sentiment of tweets relating to decisions by the video referee was significantly lower than that of other tweets: 76.24 percent of the 58,000 tweets were negative, 12.33 percent positive and 11.43 percent neutral. 

The research team also examined the average sentiment of all tweets for a given match chronologically. It turns out that the mood of tweets published after a VAR incident is significantly worse than that of tweets published before the incident.

This slump lasted 20 minutes on average. Deploying VAR in a match produces a negative sentiment on Twitter. It was this realization that led to the striking study title, rich in associations: "Video kills the sentiment".

According to the researchers the status quo is unsatisfactory, which is why they are calling on the governing bodies of the European football associations and leagues to improve the system.

"The football associations should attempt to communicate all VAR decisions with greater transparency," recommends Dr. Kolbinger. “To ensure this transparency, the associations could broadcast the communications between the referee on the field and the video referee, as it is done in field hockey. An alternative would be to introduce the option of a 'coaches challenge', as in American football. But this is all just food for thought, based on our results.”

"The research project led by Dr. Otto Kolbinger and Melanie Knopp is a pioneering achievement,” says Prof. Lames, who heads the Chair of Performance Analysis and Sports Informatics. “They deployed a technology that they developed and applied for the first time in Germany. It is an innovative and groundbreaking contribution that advances science in this area." 

“These sentiment analyzes can be used to measure reactions from audiences both quantitatively and qualitatively,” explains Prof. Lames. "In addition, we can investigate assessments and emotions, which is an extremely valuable marketing tool."