Figure 2From: Addressing the Challenge of Defining Valid Proteomic Biomarkers and ClassifiersTypical male and female peptide profiles. Distribution of a peptide included in the male-female comparative study. The frequency of the peptide ID:4356 is plotted against the natural logarithm of the measured intensity. Both profiles show a point mass at zero and a continuous component. The zero component arises because the peptide is either absent or its concentration is below the detection limit.Back to article page