Randomness in Sports

In a recent post on kdnuggets.com the author looks back at their predictions for the FIFA World Cup 2018 and states what can be learned from the results.

They have trained an ensemble model based on various ranking systems and predictions (like FifeThirtyEight or Gracenote) and predicted Germany to win the tournament. As it turned out, this has not proven to be true.

Randomness in human behavior (cannot be modelled) is stated to be one of the reasons for the model performance.

How can this be randomness in a statistical sense? I do not see a reason to include randomness here. I would have just said that something very unlikely happened and that this does not need to be an indicator for bad modelling. Is it because they ignore the difference between the actual outcome and the true class probability? Here is an example:

The predicted class probability of their model:

• GER winning: 0.24
• FRA winning: 0.12

The unknown true class probability (that they tried to model):

• GER winning: 0.19
• FRA winning: 0.17

The actual class probability:

• GER winning: 0.00
• FRA winning: 1.00