THE WECHSLER INTELLIGENCE SCALE FOR CHILDREN APPLIED TO A SAMPLE OF LONDON PRIMARY SCHOOL CHILDREN

Abstract

Summary. This study presents the results obtained on a stratified sample of London primary school children (forty boys and forty girls in each age group, at average ages 8, 9 and 10 years), tested with both the WISC and the Revised Stanford‐Binet. The internal consistency reliability of the Full, Verbal and Performance Scales (and the individual subtests) of the WISC was determined for the three separate age groups, together with correlations of the WISC with the Revised Stanford‐Binet and teachers' ratings of intelligence. A factor analysis of the sub‐test inter‐correlations at 8, 9 and 10 years is also included. Results for this London sample indicate: That for children of average and above average intelligence, a higher I.Q. is in general found on the Revised Stanford‐Binet than on the WISC when the same child is tested with both. The size of the discrepancy between I.Qs. on the two tests is too large to permit the use of the WISC as a substitute for the Revised Stanford‐Binet. The reliability coefficients for WISC Full, Verbal and Performance Scale are reasonably high for this sample, but the reliability of the individual subtests, especially for the younger children in the sample, is too low to warrant the diagnostic use of any but the most extreme deviations in sub‐test scores. The WISC is more valid and reliable at year 10 than at year 8 or 9, for this sample. The factor analysis indicates that the Scale is measuring a common factor (provisionally identified with general intelligence) which accounts for approximately 31 per cent., 37 per cent., and 42 per cent. of the total variance at years 8, 9 and 10, respectively. A second bipolar factor extracted at each age level, although barely significant, was tentatively identified as contrasting verbal and non‐verbal abilities measured by the sub‐tests, or more specifically, the tests requiring verbal comprehension with those depending on visual‐spatial concepts.