3.

Cross validation for different methods (%)

Type of validation	Sensitivity	Specificity	PPV	Correct
*, average of 100 times cross validation; **, external test sets including 3,073 people collected by a screening program in China; PPV, positive predictive value.
10%-fold cross validation*	88.63	90.80	86.65	89.93
20%-fold cross validation*	89.08	90.17	86.27	89.72
30%-fold cross validation*	89.11	90.49	86.36	89.93
Leave-One-Out Cross Validation	88.82	90.69	86.76	89.93
Back substitution	88.60	90.69	86.74	89.84
External validation**	85.68	89.40	84.59	87.89