has_metric_category has_value_concept has value type signal-to-noise ratio n-tuple ID based metric single run based metric chromatogram metric targeted compound signal-to-noise ratio quantiles From the distribution of signal-to-noise ratios at the chromatographic peak apex of a set of targeted/expected compounds (e.g., from a QC mix), the quantiles. For example, a value triplet represents the quartiles Q1, Q2, Q3. Only detected compounds contribute to the distribution. The compounds need to be confidently identified, ideally by several characteristics (e.g., mass spectrum and retention time). Comparisons will likely only make local sense where the same method of S/N calculation is applied (or overall the same software to calculate this metric, see mzQC 'analysisSoftware'). As compounds falling below the detection limit do not contribute, a loss of sensitivity may shift the quantiles less than expected; hence, they should be interpreted together with the metric 'number of detected targeted compounds'. MS MS:4000242