To evaluate the model factors sensibility measures, the EE method calculates incremental ratios called Elementary Effects. These ratios are calculated performing randomly One-factor-Ata-Time (OAT) perturbations in each model factor. In the following, we define the elementary effect related to the i-th input factor for a scalar model y(X), with X = (X 1 , X 2 , . . . , X k ) as the k input factors re-scaled to [0, 1]. Thus, we have that: