| Two major intelligence tests are widely utilized for special education classification of Specific Learning Disability (SLD) and Mild Intellectual Disability (MID) students: Stanford-Binet Intelligence Scale: Fourth Edition (SB:IV) and Wechsler Intelligence Scale for Children-Third Edition (WISC-III). Both tests have documented validity, reliability and history of research-driven development. In studies of normal subjects, WISC-III and SB:IV scores are similar and well-correlated. Studies conducted by school psychologists suggest that exceptional subjects' WISC-III scores are lower than expected compared to SB:IV or other tests.;The purpose of the study was to further investigate the research findings which suggest differences between WISC-III and SB:IV in samples of exceptional students. Based on the limited research comparing WISC-III and SB:IV, it was hypothesized that the general, verbal and nonverbal intelligence and factor scores of both tests would positively correlate, but that WISC-III group mean scores would be significantly lower than SB:IV.;Method. In conducting this nonexperimental research investigation, samples of SLD and MID special education students were obtained. WISC-III and SB:IV general intelligence, verbal intelligence and factor, and nonverbal intelligence and factor scores were collected from student records or obtained through direct test administration.;Results. Pearson correlations and correlated t tests were conducted to compare relevant combinations of scores on the two tests in the two groups. Significant positive correlations and significant group mean score differences were demonstrated (with Bonferroni correction), resulting in acceptance of all research alternate hypotheses. Thus, despite significant positive correlations between scores on the two tests, WISC-III scores were significantly lower than SB:IV for all score types in both subject groups.;Conclusions. Results of this study indicate that WISC-III and SB:IV scores are not comparable in special education SLD and MID students, as suggested by previous studies of exceptional subjects. Speculations regarding possible explanations for lower WISC-III scores are presented, including: theoretical foundations, verbal instructions/content, speed of performance, and cognitive developmental tasks. Factors contributing to confidence in and generalizability of results are described, along with contributions to the field and future research recommendations. SB:IV may be a better test choice for intellectual assessment of students referred or classified as SLD or MID. |
