ASSESSMENT OF A LARGE SCALE TESTING PROGRAM: THE WECHSLER
INTELLIGENCE SCALE FOR CHILDREN-REVISED (WISC-R)
According to Zimmermann and Woo-Sam (1994), the WISC-R is used in literally thousands of educational settings (as well as clinical settings) every year to determine the intelligence levels of students; in other words, the WISC-R is clearly an instrument comprising a large scale testing program across both clinical and educational settings. The instrument was designed---like all of the Wechsler Scales---to measure intelligence defined as,
the aggregate or global capacity of the individual to think rationally and deal effectively with the environment (Wechsler, 1944, p.3).
The definition of intelligence also includes a number of non-cognitive skills such as zest, impulse control and goal awareness (Wechsler, 1974).
The WISC-R consists of 12 subtests, although only ten are regularly administered. The subtests are grouped into two major divisions: Verbal Scales (e.g. math, vocabulary, comprehension etc.); and Performance Scales (e.g. picture completion, block design, mazes etc.). The test was standardized on 2,200 children ages six and one-half through sixteen and one-half in eleven yearly age groups with 100 boys and 100 girls included at each age level. The standardization sample was matched to U.S. Census statistics in terms of race, ethnicity, geographic regions, occupation of head of household, and urban-rural residence.
According to Brown (1988), in order to qualify as a "good test" an instrument must possess two characteristics. It must be reliable (consistently measures what it measures); and, it must be valid (accurately measures that which it purports to measure). The reliability of the WISC-R has been discussed by Zimmermann and Woo-Sam (1994) who report that split-half reliability coefficients computed for each of the 11 age levels, for each subtest, for the Full Scale,
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