PCAST 2016 Report
Definition
The President's Council of Advisors on Science and Technology 2016 report 'Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods,' which found that handwriting examination had foundational validity but that 'validity as applied' was not established due to insufficient black-box examiner studies.
- Author
- President's Council of Advisors on Science and Technology
- Year
- 2016
- Handwriting finding
- Foundational validity present, but validity as applied not established
- Reason
- Insufficient black-box examiner studies
Common questions
What is the difference between foundational validity and validity as applied in the report's terms?+
Foundational validity asks whether a method can, in principle, reliably distinguish matches from non-matches under controlled testing. Validity as applied asks whether a specific examiner, using the method in practice, reaches accurate conclusions, which the report said required separate black-box studies of examiner performance.
Why did the lack of black-box studies matter specifically for handwriting examination?+
Without studies measuring how often practicing examiners correctly identify or exclude writers under blind test conditions, there was no empirical error rate to cite in court, leaving the discipline's real-world accuracy an open question even though its underlying premise was judged sound.
Related terms
- Courtroom-Language Translation Problem
- The empirically documented gap between what forensic verbal conclusion terms (such as 'strong probability') are intended to convey by examiners and what...
- Elimination (SWGDOC)
- The most definitive negative conclusion on the SWGDOC scale, meaning fundamental differences in writing habits that cannot be attributed to disguise, natural...
- ENFSI Evaluative Standard
- The European Network of Forensic Science Institutes 'Standard for Formulation of Evaluative Forensic Science Expert Opinions' (2015/2016), which requires examiners to reason...
- Foundational Validity as Applied
- PCAST's standard requiring that a forensic discipline be validated through black-box studies measuring real-examiner error rates under realistic conditions, not just laboratory...
- Identification (SWGDOC)
- The most positive conclusion on the SWGDOC scale, meaning the examiner has found individualising agreement in all significant habitual writing characteristics, with...
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- No Conclusion (SWGDOC Position 5)
- The midpoint of the SWGDOC scale, indicating that the evidence is equally consistent with a common source or different sources. It is...
- Population-Frequency Anchoring
- The practice of grounding a conclusion about feature rarity in empirically measured frequency data for those features in the relevant writing population,...
- SWGDOC Nine-Point Scale
- The conclusion scale developed by the Scientific Working Group for Forensic Document Examination, running from 'identification' (most positive) through 'no conclusion' (midpoint)...