Comparison of Linear Equating and Prorated Short Forms for Estimating WAIS-R FSIQ in a Neuropsychological Population

Comparisons were made of estimates of the Wechsler Adult Intelligence Scale - Revised Full Scale IQ using the two-,three- and four-subtest linear equating procedures of Kaufman (1990) and Booker and Cyr (1986) with FSIQ estimates using prorating to obtain FSIQ scores. The advantage of prorating is that it affords greater clinical flexibility in selection of subtests. The participants were 64 neuropsychiatric patients who completed the full WAIS-R from which short form and FSIQ were calculated. Prorating yielded estimates of mean IQ and categorization of IQ comparable to IQs obtained by linear equating, though there was an increased likelihood of disparate results with extreme IQ scores. Prudent clinical judgment is recommended for situations involving unusual or extreme scaled score patterns, particularly when the number of subtests is small.