Distribution of the LS1 values. Box-and-whisker diagrams of the LS1 values associated with the concordant mass spectral identifications (black) and the non-concordant identifications (gray) obtained using the seven different mass spectrum libraries tested (B1 to B7). The lower and upper portions of the box represent the lower and upper quartiles, respectively. The dark band represents the median value. The ends of the whiskers represent the lowest datum included in the 1.5 inter-quartile range (IQR) of the lower quartile and the highest datum included in the 1.5 IQR of the upper quartile. Outlier values are represented by a circle; a.u.: arbitrary unit.