Simply Forensic Reference Library

Analytical Threshold

Forensic DNA & Genetics

Definition. A validated signal threshold, commonly expressed in RFU, above which electropherogram peaks are sufficiently distinguishable from analytical noise to be evaluated.

How the term is used

It governs detection of candidate peaks, not the entire process of interpretation or assessment of dropout.

Forensic example

A laboratory with a validated analytical threshold of 100 RFU flags a peak at 125 RFU for further review.

Interpretation limitation

A peak above the analytical threshold is not automatically a genuine contributor allele.

References and further reading

SWGDAM guidelines for forensic DNA analysis. The explanation and example are original educational summaries; consult the cited material and current laboratory guidance for authoritative application.

Related guide: Analytical Threshold in forensic practice.

Related glossary terms

Stochastic ThresholdA validated signal level used in some STR interpretation schemes to help assess the possibility of allelic dropout…Explore term Allelic Drop-InA detected allele-like signal that is not explained by the assumed contributors or known artefacts and may arise…Explore term Allelic DropoutFailure to detect an allele that is present in the DNA of a contributor, often because of stochastic…Explore term Combined Probability of InclusionAn estimate of the proportion of a specified population that would not be excluded as a possible contributor…Explore term

Related articles

Analytical and Stochastic Thresholds in Forensic DNA Interpretation: Validation, Dropout and Worked ExamplesA technical guide to analytical and stochastic RFU thresholds in forensic STR interpretation: baseline noise, dropout risk, laboratory…Read article Essential Guide to Low-Template DNA: Allelic Dropout and Peak Height BalanceExplore allelic dropout, stochastic PCR variation and peak-height imbalance in low-template forensic STR profiles, with five worked examples,…Read article Forensic STR Electropherogram Interpretation: Analytical and Stochastic Thresholds, Stutter, Dropout and MixturesInterpret forensic STR electropherograms using validated analytical and stochastic thresholds, stutter assessment, dropout considerations, mixture analysis and likelihood…Read article