A detectability plot corresponding to the situation from Figure 2B. Peptides in each protein are ranked according to their detectability. The identified peptides p1, p2, and p3 are shaded, while the remaining peptides are white. The situation provides intuition for a decision that protein P1 is more likely to be present in the sample than protein P2. Note that detectabilities of peptides p1, p2, and p3 are not necessarily identical in the two proteins. This is because they depend on peptide sequence but also on the context of the parent protein (neighboring peptides).