Estimating premorbid intelligence: Comparison of traditional and contemporary methods across the intelligence continuum

The present investigation compared the North American Adult Reading Test (NAART), Wide Range Achievement Test-3 (WRAT-3) Reading subtest, Barona, and Oklahoma Premorbid Intelligence Estimate Best(OPIE) premorbid intelligence estimates in 64 chronic pain patients across three intelligence ranges. Results for the entire sample revealed that the NAART, Barona, and OPIE Best equations overestimated Wechsler Adult Intelligence Scale – Revised Full Scale IQ (WAIS-R FSIQ), while the WRAT-3 underestimated FSIQ. When the sample was divided into three intelligence ranges, the OPIE more accurately classified individuals with above average intelligence, while the WRAT-3 more accurately classified individuals with below average intelligence. Three methods (NAART, OPIE, and WRAT-3) provided relatively equivalent classifications of individuals in the average intelligence range. The Barona method tended to systematically under- and overestimate FSIQ across the intelligence continuum. These results suggest the potential utility of using different estimation methods for individuals in different IQ ranges, and speak to the need for development of estimation methods that incorporate current reading ability with best performance and demographic variables.