Assessment and Testing
What this domain covers
Assessment and Testing tests psychometric concepts, score interpretation, test selection and administration, and the ethics of evaluation.
Core rules
- Reliability is consistency: test-retest, internal consistency (Cronbach's alpha, split-half), inter-rater, and parallel forms. The standard error of measurement turns reliability into a confidence band around a score.
- Validity is the adequacy of interpretation: content, construct, and criterion (concurrent and predictive). A test can be reliable and invalid, but it cannot be valid without reliability.
- Standardized norm-referenced tests compare a score to a norm group; criterion-referenced tests compare performance to a defined standard. Percentile rank is the percentage scoring at or below a score, not percent correct.
- Standard scores: z (mean 0, SD 1), T (mean 50, SD 10), stanine (mean 5, SD 2), deviation IQ (mean 100, SD 15).
- Instruments: MMPI-3, MCMI-IV, Beck Depression Inventory-II, WAIS-IV and WISC-V, Strong Interest Inventory, Self-Directed Search; Rorschach and TAT are projective measures requiring specialized training.
- ACA Section E: informed consent for assessment, competence with the instrument, appropriate norms, secure records, and explaining results to clients.
Worked example
A client scores at the 84th percentile. Reasoning: percentile 84 corresponds to z = +1.00, a T-score of 60, and a deviation IQ of 115. The counselor reports the confidence interval rather than the point score alone because measurement error applies, and notes whether the norm group is relevant to this client before interpreting.
Traps
Treating reliability as validity; confusing percentile rank with percent correct; using grade-equivalent scores as interval data; administering a test outside one's competence; ignoring test bias and norm-group mismatch.