Fig. 4: The mean R² as a function of the ‘Type of ML model’, depending whether the Time was selected as a feature or not.

Both training and testing performances were considered for all references using R² as an evaluation metric^{1,2,3,4,6,7,8,9,10,11,12,13,14,15,16,17,19,18,} (ML for corrosion database⁴³). The error bars represent the standard deviation of the mean.