Simply Forensic Reference Library

Stochastic Threshold

Forensic DNA & Genetics

Definition. A validated signal level used in some STR interpretation schemes to help assess the possibility of allelic dropout at a locus.

How the term is used

It is different from the analytical threshold and depends on the assay, conditions and laboratory interpretation framework.

Forensic example

A single allele above the analytical threshold but below a laboratory stochastic threshold may warrant dropout consideration.

Interpretation limitation

No universal RFU threshold applies across laboratories or interpretation models.

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: Stochastic Threshold in forensic practice.

Related glossary terms

Analytical ThresholdA validated signal threshold, commonly expressed in RFU, above which electropherogram peaks are sufficiently distinguishable from analytical noise…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 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 Beyond the Surface: Extending the Forensic MRI Window for Living Strangulation VictimsThe "Silent" Violence In forensic casework, few things are as frustrating as the disconnect between a victim's account…Read article