How to Calculate FSIQ WISC-IV

The Wechsler Intelligence Scale for Children – Fourth Edition, or WISC-IV, is probably the most widely used of the individually administered tests of intelligence for children in the English-speaking world. The figure for full-scale intelligence quotient, or FSIQ, is a single, easily comprehensible figure for a child’s overall intellectual ability.

Preparation

Calculate the chronological age of the child at testing by comparing the child’s date of birth to the date or dates of testing.

Inspect the WISC-IV assessment protocol for completeness. Confirm that either all core subtests are completed, or that there is an acceptable substitute provided in the protocol. Flanagan and Kaufman, Table 3.1, page 110, has a list of acceptable substitutions for core subtests, for which information is also available in the “Administration and Scoring Manual” for WISC-IV; incomplete protocols should not be interpreted further except under professional supervision.

Compare the chronological age of the person assessed to the intended age range for the WISC-IV, ages 6 to 16 years. Protocols for individuals outside the age range normally should not be interpreted further, but refer to the “Tips" for more information.

Inspect the WISC-IV assessment protocol for common errors in the calculation of raw scores, such as neglecting to include points from the items below the basal point. Flanagan and Kaufman, page 108, has a list of common errors in raw score calculation. Correct any errors you find.

Calculation

Transfer the raw scores for each subtest from the inside of the Record Form to the front cover. Convert the raw scores for each subtest to scaled scores, using Table A.1 of the “WISC-IV Administration and Scoring Manual.” Record the scaled scores in two places on the front cover of the Record Form: “Subtest Scaled Score Profile” and “Total Raw Score to Scaled Score Conversions.”

Inspect the WISC-IV assessment protocol for common errors in the calculation of scaled scores, such as looking at figures for the wrong age group. Flanagan and Kaufman, page 109, has a list of common errors in obtaining scaled scores. Correct any errors you find.

Convert the scaled scores to the following composite scores: Verbal Comprehension Index, or VCI; Perceptual Reasoning Index, or PRI; Working Memory Index, or WMI; Processing Speed Index, or PSI; and Full Scale Intelligence Quotient, or FSIQ. Use Tables A.2, A.3, A.4, A.5, and A.6 for these conversions, respectively, as found in the “WISC-IV Administration and Scoring Manual.”