Table 3. Comparison of performance estimates based on random cross-validation and cluster-cross-validation. The table provides the performances in terms of AUC averaged over the different targets for both random cross-validation and cluster-cross validation. The performance estimates obtained from random cross-validation are on average 0.02 higher, i.e., more optimistic, than the ones from cluster-cross-validation.

Cluster-cross-validation	Fold 1:	0.722 ± 0.138	Fold 2:	0.729 ± 0.148	Fold 3:	0.743 ± 0.147
Random cross-validation	Fold I:	0.747 ± 0.145	Fold II:	0.760 ± 0.136	Fold III:	0.754 ± 0.142