the Shapley value (Shapley, 1953), which has been developed in cooperative game theory to compute the distribution of the total outcome obtained by a coalition of players starting with the contribution of each player in the coalition. This concept can be extended to estimate the contribution of a single variable to a statistical indicator of goodness-of-fit of the adopted model, such as the R-squared (Huettner & Sunder, 2012; Shorrocks, 2013).