Discrepancies between IQ and index scores for a clinical sample of students: Useful diagnostic indicators?

Discrepancies between IQ and Index scores on the WISC-111 were investigated for a sample of students with SLD (n = 202), with MR (n = 115), and evaluated but not classified (n=159). Mean Verbal and Performance IQ discrepancies, though significantly different for each sample, were smaller than those reported in the WISC-III manual for the normative sample. Similarly, the Index score comparisons indicated differential functioning for the three samples, with the exception of the Verbal Comprehension and Freedom from Distractibility Index discrepancy. Moreover, the Performance IQ was higher than the Verbal IQ for all three samples. Consistent with the WISC-R literature, discrepancies between Verbal and Performance IQs and higher Performance than Verbal IQs are not diagnostic indicators of abnormalities.     

Predictive validity of the Slosson Intelligence Test with the WISC-R and the WRAT-R level 1

Slosson Intelligence Tests (SITS) administered by school guidance counselors correlated significantly with school psychologist administered WISC-Rs (r=.75). The Slosson IQ correlated significantly higher with the WISC-R Verbal IQ than with the Performance IQ score. The mean Slosson IQ was a statistically significant 4.4 points higher than the mean WISC-R Full Scale IQ (p<.01).     

A comparison of WISC and WISC-R results of urban educable mentally retarded students

Twenty urban EMR students' WISC-R scores were compared with their previously administered WISC scores. The average interval between administrations was approximately three years. Significant coefficients of correlation were obtained between five corresponding subtests and between Performance IQs and Full Scale IQs. Results from t tests for correlated data indicated that mean WISC-R Verbal, Performance, and Full Scale IQ scores were not significantly lower than their corresponding WISC scores. The results of this study indicated that WISC-R scores in comparison to WISC scores appeared to be more stable in the lower IQ ranges and less vulnerable to cultural bias.     

Relationship between PPVT and WISC-R in children with reading disabilities

The Peabody Picture Vocabulary Test (PPVT), Form A was compared to the Wechsler Intelligence Scale for Children-Revised (WISC-R) in two samples of children with reading disabilities. One group of 14 children, referred to a university clinic, were administered the WISC-R, followed by the PPVT. The second group of 38 children from a private learning disability center were administered the PPVT first, followed by the WISC-R. In the combined sample, the PPVT IQ (X̄ = 109.2) was significantly higher than the WISC-R Verbal IQ (X̄ = 98.9), Performance IQ (X̄ = 97.0), and Full Scale IQ (X̄ = 97.5). Similarly, the PPVT IQ was significantly higher than the WISC-R Full Scale in both samples separately, regardless of which test was administered first. In one case, the PPVT IQ was 50 points higher than the WISC-R IQ. Correlations between the PPVT and WISC-R Verbal, Performance, and Full Scale IQs were significant (rs = .56, .29, and .50, respectively). The results suggest that the two tests do not provide interchangeable IQs for a population of reading disabled children.     

Concurrent validity of the test of nonverbal intelligence with learning disabled children

Results of the TONI, WISC-R, and WRAT were compared for a sample of 66 learning disabled children: 51 males (32 white, 19 black) and 15 females (9 white, 6 black) whose mean age was 9–5 (SD = 1–10). The mean score of the TONI was significantly different from the Performance IQ. Nonsignificant differences were found between the TONI and Full Scale IQ and between the TONI and Verbal IQ. Correlation coefficients between the TONI and WISC-R ranged from a low of .35 for the Verbal IQ to .44 for both the Full Scale and Performance IQs. The correlation coefficients between the TONI and standard scores of the WRAT were .38, .27, and .23, for Reading, Spelling, and Arithmetic, respectively. Implications of these findings are discussed.     

The relationship between the WAIS-R and academic achievement among EMR adolescents

This study examined the relationship between the WAIS-R and WRAT-R among 78 EMR adolescents enrolled in resource classes in a public school setting. Results indicated that the WAIS-R Verbal IQ was significantly correlated with all WRAT-R subtests (r range = .66 to .77). The Performance IQ was found to be significantly related only to Arithmetic (r = .26). The Full Scale IQ was significantly related to Reading (r = .25) and Arithmetic (r = .56), but not Spelling. Results suggest that the WAIS-R Verbal IQ and Full Scale IQ generally show moderate correlations with achievement but the Performance IQ generally shows no or little relationship to achievement. This pattern of findings is somewhat different from prior Wechsler research with other populations. Implications for the diagnostic activities of school psychologists are discussed.     

A longitudinal study of the WISC-R and WAIS-R with special education students

The relationship between the WISC-R and WAIS-R was studied in a sample of 30 special education children (22 male and 8 female). Children were administered the WISC-R at an average age of 13.85 years and the WAIS-R at an average age of 17.52 years. ANOVAs indicated that the two tests yielded Verbal, Performance, and Full Scale IQS that were not significantly different. For example, the mean Full Scale IQ was 81.13 for the WISC-R and 82.70 for the WAIS-R. Product-moment correlations also were highly significant, with rs ranging from .76 to .86 for the three scales. The results suggest that, for children of limited intelligence, the WISC-R and WAIS-R provide comparable IQs over a four-year time period.     

The relationship between the Kaufman Brief Intelligence Test (K-BIT) and the WISC-R with referred students

The K-BIT and the WISC-R were administered in counterbalanced order to 35 referred students. Although the K-BIT IQ Composite correlated significantly with the WISC-R Full Scale IQ scores (r=.81), the mean scores differed significantly (difference = 6.2 points; p<.001). The results provide moderate support for the K-BIT as a screening instrument when the WISC-R is the follow-up or comprehensive measure of intelligence.     

Correlations between WISC-R subtests and verbal,performance, and full scale IQ scores for minority group children

The relationship between WISC-R subtest scores and Verbal, Performance, and Full Scale IQs was investigated for a sample comprised of rural Appalachian children. The sample was comprised of both white and black children who might be described as culturally different by virtue of low family income and residence in the mountainous areas of Virginia and North Carolina. Data analysis consisted of computing product-moment correlations (rs) between each of the ten subtests and the Verbal, Performance, and Full Scale IQs. Correlations between individual subtests and the FS IQ ranged from.49 through.63, but none of the differences between these rs were large enough to attain significance. Correlations between the verbal subtests and Verbal IQ ranged from.64 for Comprehension up to.78 for Vocabulary. For the performance subtest, the rs ranged from.54 between Coding and the Performance IQ up to.72 for Object Assembly.     

Screening for giftedness with the Slosson and the scale for rating behavioral characteristics of superior students

Children who had been nominated as potential candidates for gifted programs were assessed to determine the relationships among certain behavioral and intellectual characteristics. Records were compiled listing 132 first- through eighth-grade children's race, sex, age, grade level, Slosson Intelligence Test (SIT) IQ scores, Scale for Rating Behavioral Characteristics of Superior Students (SRBCSS) scores, and WISC-R IQs. Only children achieving SIT IQs of 130 or higher were included. A regression equation for the prediction of a WISC-R Full Scale IQ score from a given SIT score was computed and compared to that developed for predicting the WISC-R IQ in another study. All variables except SIT IQ were poor predictors of WISC-R IQ scores. A moderate correlation was computed between SIT and WISC-R Verbal and Full Scale IQ scores. A somewhat lower, but still significant, degree of relationship was found between SIT and WISC-R Performance IQ scores. Some difficulties with using the SIT as a screen for gifted programs are discussed.     

Validation of the Stanford-Binet Intelligence Scale: Fourth edition with exceptional black male students

Standard Age Scores on the Stanford-Binet Intelligence Scale: Fourth Edition (SBIV) and WISC-R IQs of 51 urban black males receiving special education services were compared. Correlations between the SBIV Composite scores and WISC-R Verbal, Performance, and Full Scale IQs were 0.803, 0.826, and 0.87 respectively. Correlations between all combinations of scales ranged from 0.612 to 0.888, median r=.723. SBIV Composite mean scores did not differ significantly from the mean WISC-R Full Scale, Verbal, and Performance IQs. Regression analysis of the three subgroups (BD. LD, and EMR) indicated that the SBIV possesses differential validity for each group. Tabular comparison of precision of classification between the SBIV and the WISC-R yielded a 78% agreement. These data suggest that the SBIV possesses utility for assessing the intelligence of black students classified as BD and EMR. However, the use of the scale with LD students is unsupported.     

The role of sex differences in the referral process as measured by the Peabody Picture Vocabulary Test-Revised and the Wechsler Intelligence Scale for Children-Revised

The Peabody Picture Vocabulary Test-Revised (PPVT-R) and the Wechsler Intelligence Scale for Children-Revised (WISC-R) are two tests that are often used in the assessment process for special education referrals. Sex differences apparent in these tests were examined in a sample of Arkansas school children who were first-time referrals for a psychological evaluation. The subjects' PPVT-R standard scores, WISC-R IQ scores, and WISC-R subtest scores were divided into groups according to one-year intervals from ages 6 through 16. A separate 2 × 11 (subjects' sex x subjects' age) analysis of variance was performed for each dependent variable. Results indicated significant sex differences among WISC-R Full Scale, Verbal, and Performance IQs and PPVT-R standard scores (p < .01). Several WISC-R subtests also revealed significant sex differences. Further significant sex differences were indicated at several age groups on each dependent variable, with males consistently scoring higher than females on 87%. of the dependent measures excluding the WISC-R subtest Coding, on which females scored higher. Implications concerning the referral process are discussed.     

Stability of WISC-R scores in children with learning difficulties

Student records of 130 children with learning difficulties who had been tested twice were examined to determine the stability of WISC-R scores over time. There were significant losses in Verbal IQ and Full Scale IQ. Subjects in the above-average IQ range had greater losses in Verbal IQ and Full Scale IQ and greater gains in Performance IQ than did those in the below-average IQ range. Children initially tested before age 8 had a significant IQ loss, but those tested after age 8 maintained a constant IQ. The WISC-R is most frequently administered to children with learning difficulties. Results presented here suggest that the IQs in this population are not as stable as was previously thought, and this may provide a rationale for the periodic readministration of the WISC-R.     

Comparison of scores for intellectually gifted students on the WISC-R and the fourth edition of the Stanford-Binet

The WISC-R and the Fourth Edition of the Stanford-Binet (SB: FE) were compared in the identification and assessment of 48 intellectually gifted students in the primary and secondary grades. While only a 3.2-point difference between the mean SB: FE Composite score and the mean WISC-R Full Scale score was found, (r = .393, p. ⩽ .01), the t test between the two scores was significant (t = 2.30, p ⩽ .05). Correlations between the three scales of the WISC-R and the SB: FE four broad area and Composite scores ranged from −.219 (SB: FE Abstract/Visual Reasoning with WISC-R Verbal) to .599 (SB: FE Short-Term Memory with WISC-R Full Scale). Within the correlational matrix, only 5 of the 15 correlations were significant. Both the SB: FE Abstract/Visual Reasoning and Quantitative Reasoning Area scores had no significant correlations with any of the WISC-R scores.     

A longitudinal comparison of the WISC and WISC-R with special education pupils

The purpose of this study was to determine the degree of comparability between the WISC and the WISC-R over time. Hypotheses were tested using a sample of 276 mildly mentally handicapped children enrolled in special education classes who had received a WISC (Trial 1) and a WISC or WISC-R (Trial 2) after an interval of approximately three years. The sample was grouped on the basis of test administered in Trial 2. Group I contained those children who received the WISC on Trial 2 and included 183 children, of whom 121 were males and 62 were females. Mean age at time of initial testing was 8–10; mean age at second testing was 11–8. Group II was composed of 93 children who had been posttested on the WISC-R and included 72 males and 21 females. Mean age at initial testing was 9–5; mean age at posttest was 13–0. The study was conducted in five school districts and one county department of education. Verbal IQ, Performance IQ, and Full Scale IQ for both instruments administered were transcribed from the special education folders of the children. The design used to test hypotheses was repeated measures analysis of variance. Data analysis resulted in rejection of the hypotheses that the WISC-R yields mean Verbal, Performance, and Full Scale IQ scores greater than or equal to the corresponding mean IQ scores of the WISC. It was concluded that the WISC-R may unfairly penalize special education children who are reevaluated with this instrument. Fluctuations in IQ scores due to the instrument of measurement must be recognized, and appropriate action should be taken to insure that children are evaluated for special class placement on comparable bases.     

Stability of WISC-R intelligence scores: Implications for 3-year reevaluations of learning disabled students

Student records of 170 learning disabled students from two area agencies were examined to determine the stability of WISC-R test scores administered as part of the 3-year reevaluation of students required by Public Law 94–142. The WISC-R had been readministered to 150 of these students. Stability coefficients were .72, .70, and .74 for the Verbal, Performance, and Full Scale IQ scores. Changes in Full Scale scores were 4 points or less for 52% of the sample. Changes greater than 15 points were noted for 4% of the sample. Results suggest that WISC-R scores are reasonably stable over a 3-year interval, and routine readministration of the WISC-R should not be required or encouraged.     

Similarity of WISC-R and WAIS-R scores at age 16

Thirty learning disabled students of average intellectual ability between 16 and 17 years of age were given both the WISC-R and the WAIS-R to determine if the WAIS-R provided higher average IQ scores, as had been reported for educationally mentally retarded adolescents. The results indicated: (a) no significant differences between the two scales on either the Verbal, Performance, or Full Scale IQs, (b) significant correlations between the WISC-R and WAIS-R on the three IQ scores and 9 of the 11 subtests, and (c) the emergence of the ACID profile for learning disabled adolescents on both tests.     

The relationship between the WISC-R and WRAT-R for a sample of rural referred children

WISC-R Verbal and Performance IQ scores obtained from a sample of 124 referred children were correlated with WRAT-R achievement scores. The Verbal IQ was found to predict Reading, Spelling, and Arithmetic. The Performance IQ did not add significantly to the predictions. The results were consistent with earlier studies that examined the relationship of the WISC-R to the WRAT.     

The long-term stability of WISC-R scores in mildly retarded and learning-disabled children

This study addresses the need for systematic longitudinal research documenting the stability of WISC-R scores in special education populations. WISC-R scores of 100 learning-disabled and 60 mildly retarded children retested on three separate occasions at three-year intervals were examined. The stability of WISC-R scores was evaluated according to three different criteria: (a) the consistency of group means over time, (b) the frequency of significant changes in individual scores, and (c) correlations between administrations as an index of stability of subjects' relative positions in the group. Different results were obtained depending on the criterion considered. Examination of group means and correlation coefficients indicated that Full Scale IQ was fairly stable over a period of six years for both learning-disabled and mildly retarded samples. However, greater variability was noted when examining the frequency of changes in individual subject's scores. Verbal IQ and Performance IQ demonstrated somewhat more variability by all criteria examined. The implications of these results with regard to the importance assigned to IQ in special education classification decisions, the usefulness of retesting IQ in three-year reevaluations, and the efficacy of special education are discussed.     

Comparison of the PPVT-R and WISC-R with urban educable mentally retarded students

Comparisons of the revised PPVT (PPVT-R) and the WISC-R were made with 67 EMR students. Significant differences were found between the PPVT-R mean standard scores and Verbal, Performance, and Full Scale IQs. The PPVT-R did not correlate significantly with the WISC-R scales or subtests, suggesting the tests are measuring different abilities.