What do Andrea Iniesta, Christen Eriksen, Radamel Falcao and Fyodor Smolov all have in common?
The answer is that each took the opening penalty kick in one of the four shootouts at the 2018 FIFA World Cup in Russia. What is more interesting is that all four ended on the losing side. For those familiar with penalty shootouts, and recent rule changes, it should come as a surprise that the team kicking first lost on all four occasions.
Last October, I wrote about rules changes that have been initiated by some football associations, including the Football Association (FA), altering the structure of the penalty shootout. The traditional ABAB sequence (where team A shoots first, followed by Team B, back to Team A, and so on) has been replaced by ABBAA system.The need for this change was highlighted by a 2010 paper in the American Economic Review by Jose Apesteguia and Ignacio Palacios-Huerta called Psychological Pressure in Competitive Environments: Evidence from a Randomized Natural Experiment.
The authors demonstrate that the team kicking first, had a persistent and statistically significant advantage, winning roughly 60% of the time. The 2018 World Cup goes against these findings. Our course, with a sample size of just 4 this is entirely possible. The 60/40 split from the 2010 study is based on a data-set comprising 1,343 penalty kicks from 129 penalty shoot-outs over the period from 1970 to 2003.
It begs the question however, if the sample was increased or decreased how would the results change? If we had data on 5,000 shootouts would a statistically significant result prevail?