Precision-recall curves evaluated on the test sets for the fiducial balanced model (top panel), optimistic balanced (middle panel), and pessimistic balanced (bottom panel). The colors indicate the results we obtained for different folds. F1 is reported as a scoring parameter for each fold and has been evaluated by applying a threshold equal to 0.5 on p(j ∈ k|x, d_j) (see Sect. 2.5 for details). The dashed horizontal red line represents the precision-recall curve of a classifier making random guesses.