Figure 9

Semiparametric fits with dynamically estimated coefficients. Semiparametric fits of the distributions of scores for correct and incorrect identifications on the Controlled Mixture Dataset from a constrained search (tryptic peptides, narrow mass tolerance) using fixed discriminant coefficients (left) versus adaptive discriminant coefficients (center). The right tail of the distribution of scores for incorrect identifications can be seen penetrating the distribution of scores for correct identifications more deeply in the fixed case implying greater discriminative ability when using the adaptive discriminant function. The improved performance of adaptive coefficients can be seen in the plot of the estimated FDR versus the estimated number of significant correctly identified spectra (right). Recall that in this dataset, target scores are assumed correct. The estimated FDR here was estimated by the ratio of the number of decoys to target scores.