Are soccer players from violent countries more likely to get yellow cards?

A new study [pdf] by three researchers purports to show that soccer players in European leagues who come from countries with histories of civil war are more likely to play violently on the field, as measured by their tendency to get yellow and red cards. Check out the chart here— and notice that the two countries nearly off the grid are Colombia and Israel.

So does growing up in a violent country mean you’ll be a dirtier soccer player? Well, not necessarily. There are, of course, a couple problems with the study:

  • As any Stat 101 student knows, correlation does not imply causality. Perhaps the soccer played in certain countries– Colombia, Israel, Ivory Coast, Georgia– is just more physical than the soccer in Europe.
  • Maybe the referees are biased.
  • Maybe the players are getting yellow cards for diving rather than hard tackles.
  • Maybe a lot of things.

Despite these apparent problems, I find the study ingenious and fascinating. As the study says: “Beyond providing a novel real-world measure of individuals’ willingness to commit acts of violence, this finding indicates that some aspects of national culture are persistent even when individuals are far from home in a different institutional setting, here, a professional sports league.”

More here.