Results of shared peptides of Mix 1. This figure illustrates the identification results of shared peptides of Mix 1. It is shown that IM outputs all true shared peptides of Mix 1 regardless of threshold, while this number from PeptideProphet decreases rapidly with the increase of the threshold. In addition, IM outputs a constant number of false positive shared peptides. This is because these peptides are from one false positive protein, of which the constituent peptides are given in Table 2.