Time-varying ratings for international football teams

We present a model for rating international football teams. Using data from 1944 to 2016, we ask 'which was the greatest team?'. To answer the question requires some sophisticated methodology. Specifically, we have used k-fold cross-validation, which allows us to optimally down-weight the results of friendly matches in explaining World Cup results. In addition to the central aim of the paper, we also discuss, from a philosophical perspective, situations in which model over-fitting is perhaps desirable. Results suggest that Hungary in 1952, is a strong candidate for the all-time greatest international football team.