Academic journal article Mankind Quarterly

Local Norms for Some Subtests of the Third Version of Wechsler Intelligence Scale for Children (WISC-III) in Gifted Schools in Khartoum

Academic journal article Mankind Quarterly

Local Norms for Some Subtests of the Third Version of Wechsler Intelligence Scale for Children (WISC-III) in Gifted Schools in Khartoum

Article excerpt

The Wechsler Intelligence Scales for Children (WISC) have been extensively used in the identification of gifted children in countries where special educational programs for these children exist (e.g., Bishay, 1981; Colangelo & Davis, 2003). This has been confirmed in a recent survey of 300 school psychologists (members of the National Association of School Psychologists) working in elementary schools in the USA (Robertson et al, 2011). 51.3% of the school psychologists used WISC-III as the main instrument for the identification of gifted students. This is the highest percentage among 14 identification instruments included in the survey. The second most extensively used instrument, the Stanford Binet test, only attained 17.7%.

The third edition of the Wechsler Intelligence Scale for Children (WISC-III) was issued in 1991 (Wechsler, 1991). It is a modified version of the first scale (WISC) that was issued in 1949 (Wechsler, 1949) and the second scale (WISC-R) that was issued in 1974 (Wechsler, 1974). WISC-III (for children from 6 to 16 years) consists of 13 subtests. Six of the subtests are verbal: information, vocabulary, comprehension, arithmetic, digit span, and similarities. The other 7 subtests are performance-based: picture completion, picture arrangement, block design, mazes, object assembly, coding, and symbol search. The scale yields three intelligence quotients: verbal IQ, performance IQ and total IQ. The scale also yields 4 mental indices. These are verbal comprehension, perceptual organization, freedom from distractibility, and processing speed (Nicholson & Alcorn, 1993).

Many intellectual giftedness specialists and researchers favor WISC-III and recommend using it to identify gifted individuals (e.g. Fishkin et al, 1996; Kaufman, 1992; Mark et al, 1998; Panicker, 2005; Prifitera et al, 1998; Reiter, 2002, 2004, Rimm et al, 2008; Sweetland et al, 2006). Some studies were conducted to compare WISC-III with other individual intelligence tests. For instance, WISC-III was compared with the fourth edition of the Stanford Binet test (Mullins, 1999; Simpson et al, 2002). WISC-III proved to be more effective in identifying gifted individuals. It correlated highly with other identification instruments. Minton and Pratt (2006) compared it with the fifth edition of the Stanford Binet. Gifted and highly gifted individuals scored higher on WISC- III, which reveals that it is more reflective of their giftedness. Other studies compared WISC-III with the revised WISC (e.g. Sevier et al, 1994). No study, to the best of the researcher's knowledge, compared the third and fourth versions of the scale among gifted individuals. The studies that were conducted compared the two versions for the diagnosis of several clinical groups and special education categories. All studies confirmed the effectiveness of WISC-III in diagnosing these categories. WISC-III was also used as a criterion to establish the validity and reliability of other identification instruments (e.g. Kimberly, 2004; Kluever et al, 1995; Koehn, 1998; Levinson & Folino, 1994a,b). Finally, the study by Fishkin et al (1994) revealed that WISC-III has no gender bias when used to identify giftedness of boys and girls.

One requirement of measurement and diagnosis is the presence of test norms. Raw scores in themselves are meaningless and difficult to interpret unless fitted in a reference system that makes comparisons possible (Abo-Hatab et al, 1987; Alaam, 2000; Aladili, 2011; Alnabhan, 2004; Atteriri, 1997). There should be a statistical criterion for comparing an individual against the group to which s/he belongs (Farahat, 2007). Norms represent the performance of a given population on a given test (Alawi & Radwan, 2000). They are derived statistically from raw scores of a representative sample of the study population (the standardization sample). The norm is used to compare the raw score of each individual with the mean of the group to which s/he belongs (Mansi, 1997; Rabia, 2002). …

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