Neuropsychologists administer and interpret a large number of tests during an assessment. It can be under-appreciated, however, that interpreting multiple test scores is different than interpreting a single test score. Multiple scores have scatter, intra-individual variability, and higher prevalence rates of ‘abnormal’ findings than a single score, so they must be interpreted simultaneously (i.e., multivariate base rates; MVBRs). This webinar will review the psychometric principles associated with MVBRs of low scores: (1) low scores are common across all test batteries; (2) the number of low scores depends on the cutscore used; (3) the number of low scores depends on the number of tests administered; (4) the number of low scores varies by examinees’ demographics; and (5) the number of low scores varies by examinees’ intelligence. Examples using pediatric, adult, and older adult data will demonstrate these principles. Newer studies considering the MVBRs of reliable change scores will also be introduced.

After the webinar, participants will be able to:

1. Describe the psychometric principles for interpreting multiple test scores.
2. Explain that there is variability in test scores and that low scores are common in healthy people.
3. Apply multivariate base rates in everyday clinical practice as an interpretive technique to reduce misdiagnoses of cognitive impairment.
4. Critique the practice of over-interpreting an isolated low score.

Target Audience: Neuropsychologists and psychologists at all career levels who assess children, young adults, and older adults

Instructional Level: Intermediate