Fig. 4

Validation of the serum peptidome biomarker model for classifying CNT/F worker exposure. a The performance of the top-five peptide model was assessed by cross-validation where the average class probabilities for validation subjects were plotted. Ideal classification was demonstrated as illustrated within the confusion matrix table. b To rule out model over-fitting, the full complement of 3,532 reproducibly detected peptides (without any supervised selection) was assessed by unsupervised principal component analysis where 43.5% of the serum peptidome variance could be explained by worker CNT/F exposure level