Forensic Assessment Instruments and Test Selection
Test selection
Forensic test selection is legally driven: the instrument must match the legal question, the examinee's population, and the referral. The exam tests psychometrics, response bias, and admissibility rather than brand-name recall alone.
Core rules
- Reliability and validity are necessary but not sufficient; sensitivity, specificity, base rates, and standard error matter.
- Use multiple methods: interview, collateral records, and tests; no single score decides a legal issue.
- Evaluate response bias with validated measures such as TOMM, SIRS-2, and MMPI-2-RF validity scales, but do not overdiagnose malingering from one index.
- Select instruments with norms matching age, education, language, and setting.
- Apply Frye or Daubert criteria and explain limitations.
Worked example
A personal-injury claimant scores below chance on the TOMM and has inconsistent effort on the MMPI-2-RF. The evaluator should not stop at "malingering." They should integrate records, interview, and collateral, rule out genuine impairment, and state confidence carefully. Reasoning: validity tests are probabilistic; a single failure is evidence, not proof.
Traps
Using tests outside validated populations; treating an actuarial score as a legal conclusion; ignoring base rates; relying on one instrument; calling low scores "brain damage" without differential diagnosis.