Semisupervised estimation of parameters. Semisupervised estimation of parameters of the same distribution of scores as in Figures 2b and 2a. For Charge 3 the slight rightward shift of the Gamma distribution (distribution of scores for incorrect identifications) also encouraged a large rightward shift of the Normal Distribution (distribution of scores for correct identifications). The two vertical lines indicate the means of the Normal distributions. The addition of decoys for Charge 2 allowed to algorithm to learn that most of the identified spectra with scores from 0 to 1 are likely to be incorrect. Without decoys this may have been overlooked.
Ma et al. BMC Bioinformatics 2012 13(Suppl 16):S1 doi:10.1186/1471-2105-13-S16-S1