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The current research aimed at adaptation and validation of the Verbal Comprehension Index (VCI) subtests of WISC-IV (Wechsler, 2004) in Pakistan. Study-I was concerned with the adaptation of VCI subtests. Initially problems in the items of original VCI subtests regarding the difficulty level and cultural relevance were identified. Then five items of vocabulary and four items of information subtests were replaced. Afterwards, item functioning and psychometric strength of the adapted Verbal Comprehension Index (VCI-P) subtests was assessed. Study-II (n = 801) was concerned with the establishment of reliability and validity evidence for the VCI-P. The stability coefficients ranged from .79 to .98, while alpha reliability coefficients ranged from .72 to .88. Structural validity was established through inter-subtests correlations (ranging from .63 to .78) and subtest-total correlations while factorial validation resulted in existence of a single factor.
Keywords: adaptation, validation, item functioning, psychometric strength.
Intelligence testing with its strong history and ever growing scope can be regarded as "mother of psychometrics". Like many other developing countries, intelligence testing has gained much attention in Pakistan for educational, clinical, and research purposes. Many intelligence tests are in use in Pakistan by different organizations and testing services (Mahmood, 1991). Some efforts have been made to develop indigenous intelligence tests for use in Pakistan but due to limited resources, these efforts can not be considered as satisfactory. First, most of these tests are non-verbal in nature while in educational research measurement of verbal intellectual ability is of much importance (Gardaizi, 2001). Secondly, most of these tests are not standardized adequately, so due to limited normative data, they are not applicable or interpretable through out the country. Moreover, most of them are not following the recent intelligence testing trends as they are relying on the old dichotomy of verbal/non-verbal and verbal/performance intelligence for their interpretation (see for example Test of Intellectual Development for Pakistani pre-school children; Abbas & Israr, 1990, Group Verbal Intelligence Test; Hussain, 2001, & Indigenous Non-verbal Test of Intelligence; Gardaizi, 2001). In the presence of such difficulties like having limited resources and expertise, it is more practical to adapt already existing well-established tests against local criteria and context (Hambleton & Pastula, 1999).
Test adaptation involves balanced handling of psychological, psychometric, linguistic, cross-cultural, and cultural considerations in...