SWGDOC Nine-Point Scale
Definition
The conclusion scale developed by the Scientific Working Group for Forensic Document Examination, running from 'identification' (most positive) through 'no conclusion' (midpoint) to 'elimination' (most negative), with seven intermediate probability positions.
- Used in
- US document examination, particularly handwriting comparison via the ACE-V method
- Total positions
- Nine: one positive endpoint, one negative endpoint, one neutral midpoint, and seven intermediate positions
- Purpose
- Standardize how forensic document examiners express the strength of their conclusions
Common questions
What is the SWGDOC nine-point scale used for?+
The SWGDOC nine-point scale is a standardized conclusion framework used by US document examiners when comparing handwriting. It lets examiners express their findings on a clear spectrum from positive identification through no conclusion to elimination, rather than forcing a binary yes/no answer.
What are the endpoints of the scale?+
The scale runs from 'Identification' at the most positive end to 'Elimination' at the most negative end. The midpoint, 'No conclusion,' represents cases where the examiner cannot determine whether documents match or don't match based on the evidence.
How many positions are on the full scale?+
The scale has nine positions total. It includes Identification and Elimination at the extremes, No conclusion in the middle, and seven intermediate probability positions that allow examiners to express varying degrees of confidence in their findings.
Related terms
- ACE-V
- Analysis, Comparison, Evaluation, Verification: the four-stage method for latent print examination used by accredited forensic fingerprint laboratories. Analysis examines the latent in...
- Analysis Phase
- The first ACE-V phase: the questioned writing is examined in isolation, individual features are catalogued, and the documentation is locked before the...
- Comparison Phase
- The second ACE-V phase: the catalogued features of the questioned writing are evaluated against the exemplar set, documenting both similarities and differences...
- 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...
- Daubert Criteria
- The four criteria a US federal court applies to assess the admissibility of expert scientific testimony: has the methodology been tested, has...
- 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...
- Evaluation Phase
- The third ACE-V phase: the combined weight of similarities and differences is expressed as a conclusion on the SWGDOC nine-point scale or...
- 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...
- Linear ACE-V
- An implementation of ACE-V methodology that enforces strict sequential documentation: analysis of the latent mark must be completed and recorded before the...
Explained in these topics
- The ACE-V Method for Handwriting ComparisonThe conclusion scale used in US document examination: Identification, Strong probability, Probability, Indications, No conclusion, Indications did not, Probabl...
- Conclusion Scales: SWGDOC, ENFSI and Courtroom LanguageThe conclusion scale developed by the Scientific Working Group for Forensic Document Examination, running from 'identification' (most positive) through 'no con...