Psychological Reports, 1979, 44, 735-738. @ Psychological Reports 1979

CORRELATIONS OF THE WECHSLER INTELLIGENCE SCALE FOR CHILDREN-REVISED, PEABODY PICTURE VOCABULARY TEST, AND SLOSSON INTELLIGENCE TEST FOR A GROUP OF LEARNING DISABLED STUDENTS~ HUBERT "BOONEY" VANCE James Madison University

RENA LEWIS San Diego State University

SUSAN DE BELL Morganlon, Norch Carolirta Swmmary.-This study compared scores on the Wechsler Intelligence Scale for Children-Revised, Peabody Picture Vocabulary Test, and Slosson intelligence test for 64 students (45 boys, 19 girls) who ranged in age from 7-3 to 13-2. Mean I Q on the Peabody was significantly higher than the mean I Q on the Wechsler Intelligence Scale for Children-Revised and on the Slosson. The mean IQs were 95.0 for the Peabody, 89.0 for the Slosson, and 87.8 for the Wechsler Full Scale, with standard deviations of 12.3, 11.7, and 7.0, respectively. Highest correlations of IQs were between Verbal Scale of the Wechsler and the Slosson (.81) and between the Verbal and Performance Scales of the WISC-R (.73).

A number of studies have investigated the correlations of the Wechsler Intelligence Scale for Children (Wechsler, 1949) and shorter intelligence tests such as the Peabody Picture Vocabulary Test (Dunn, 1963) and the Slosson intelligence test (Slosson, 1963). Such research has been done with various groups of retarded and learning disabled children. Sattler (1974) reported correlations ranging from .36 to .94 (median of .66) between IQs on the WISC Verbal Scale and Peabody and .30 to .SO (median of .63) between the Full Scale WISC and Peabody for retarded children. Correlations between WISC Performance Scale and Peabody ranged from .21 to .74 (median of .54) according to Sattler (1974). In a recent sntdy, Vance, Pritchard, and Wallbrown (1978) compared IQs on the WISC-R (Wechsler, 1974) and Peabody for a group of educably mentally retarded students and found that IQs from these two tests should not be considered interchangeable. A relatively low correlation obtained between the Peabody and WISC-R Performance Scale, suggesting that the Peabody may not be sensitive to the cognitive processes tapped by the WISC-R Performance Scale. Covin (1977) compared the Slosson and WISC-R IQs for a group of special education candidates and reported that the Slosson tends to overestimate the WISC-R Verbal, Performance and Full Scale IQ scores, and correlations between the Slosson and WISC-R were moderate to high and in individual cases a wide variety can be expected. 'Requests for reprints should be addressed to Booney Vance. Director, Child Development Clinic, James Madison University, Harrisonburg, Virginia 22807.

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The purpose of the present study was to compare the Peabody, Slosson, and WISC-R for children and youth classified as learning disabled. Correlations among IQs were computed. The 1974 revision of the Wechsler Intelligence Scale for Children (Wechsler, 1949), the WISC-R, was used as the criterion of concurrent validity. METHOD The data were collected from 64 students (45 boys, 19 girls) whose chronological ages ranged from 7-3 to 13-2, with a mean of 9-2. There were 40 white subjects and 24 black subjects who lived in rural areas of North Carolina and Virginia. All students were from middle socio-economic families. Grade placement ranged from the second to the seventh, with a mean grade placement of 4.3. Srudents were classified as learning disabled on the . basis of their psychological-educational data, school reports, discrepancy formula between ability and achievement, and medical data as well as local and stace eligibility criteria. The instruments were administered by a certified school psychologist in the fall of 1977 and the order was counterbalanced. Pearson-Corr program from the Statistical Package for the Social Sciences (Nie, Hull, Jenkins, Steinbrenner, & Bent, 1975) was used to analyze the data. Tests of significance were computed to determine significant differences in IQs from the various tests. RESULTSAND DISCUSSION Means, standard deviations, t ratios and rs for the individual tests are presented in Table 1. Mean IQs and standard deviations for the instrurnencs were for the Peabody 95.0 (SD 12.3), for the Slosson 89.0 (SD 11.7), and for the WISC-R Full Scale 87.8 (SD 87.8), the Verbal Scale 87.7 (SD 9.3), and the Performance Scale 90.1 (SD 9.4). The resulting t ratio for Peabody and Slosson IQs was significant ( p = .01); no differences were found between the Slosson and the three IQs of the WISC-R. The Peabody IQ was significantly higher than the three IQs of the WISC-R ( p = .01). IQs from the Peabody and Slosson tend to be more variable than those from the WISC-R as their standard deviations were larger. Pearsonian intercorrelations among the several variables are given in Table 1. A pattern of positive correlations was obtained between the Slosson IQ and Peabody IQ, between the Slosson IQ and WISC-R Verbal IQ and Full Scale IQ, between the Peabody IQ and Verbal and Full Scale of the WISC-R, and between the Verbal and Full Scale of the WISC-R. The rather weak correlations between the Slosson and Peabody scores are not surprising in light of differences in items on the tests. Highest correlations (.81) were obtained between the Slosson IQ and Verbal IQ of the WISC-R. One might expect a higher correlation between these scales as the items of the Slosson and Verbal

WECHSLER/SLOSSON SCORES OF LEARNING DISABLED CHILDREN 737 TABLE 1 MEANS,STANDARD DEVIATIONS, t RATIOS AND CORRELATION COEFFICIENTS, FOR IQs ON SLOSSONINTELLIGENCE TEST,PEABODY P I C ~VOCABULARY E TEST, AND WECHSLER INTELLIGENCE SCALEFOR CHILDREN-REVISED Test M Slosson 89.0 Peabody 95.0 Slosson 89.0 Wechsler Intelligence Scale for Children-Revised 87.7 Verbal Scale Performance Scale 90.1 Full Scale 87.8 Peabody 95.0 Wechsler Intelligence Scale for Children-Revised 87.7 Verbal Scale IQ Performance Scale IQ 90.1 Full Scale IQ 87.8 WISC-R Scales Verbal IQ-Performance IQ Verbal 10-Full Scale I 0 performance IQ-Full scale IQ

SD 11.7 12.3 11.7 9.3 9.4 7.0 12.3 9.3 9.4 7.0

t

-3.93

r .48

1.46 0.GO 0.99

.81 .003 .59

4.93* 2.69* 5.02"

.43* .12 .40+

Scale have greater heterogeneity. Lowest correlations were obtained between the WISC-R Performance IQ and the IQs of the Peabody (.12) and Slosson (.003). Within the WISC-R, highest rs were obtained between the Verbal and Full Scale IQs (.73) and between the Performance and Full Scale IQs (.69). This finding is expected in terms of the good construct validity of the WISC-R. The Slosson and Peabody seem to be measuring intellectual skills more akin to those tapped by the Verbal than the Performance section of the WISC-R. The present findings suggest that the Slosson is more valid than the Peabody in terms of the range of abilities assessed by the WISC-R. The Slosson and Peabody are related to the WISC-R Verbal and Full Scale IQs and, therefore, are appropriate for preliminary screening of students suspected of having learning disabilities. The decision to use the Peabody or Slosson seems a matter of the purpose for which the test is being administered. If the clinician wishes more information which might provide ideas for recommendations for remediation, then the Slosson might be used with children and youth similar to those in this study. The authors support Pikulski's contention ( 1973) that, if instruments like the WISC-R provide measures by which screening devices are to he compared, although the correlation might be high, in individual cases there could be wide variability. In this study one student earned IQs of 78 on the Slosson, 92 on the Peabody, and 70 on the WISC-R. Discrepancies as large as these could lead to gross misinterpretations; scores from the Peabody and Slos-

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son should not be considered interchangeable. This finding supports work by Covin ( 1977) and the contention of Vance, Pritchard, and Wallbrown ( 1978) char scores from the Peabody and Slosson should not be substicuced for those of the .WISC-R, at least for both black and whice rural children with learning problems. REFERENCES COVIN,T. M. Comparison of SIT and WISC-R IQs among special education candidates. Psychology i n the Schools, 1977, 14, 19-23. DUNN, L. M. Exfianded manual for the Peabody Picture Vocabulary Test. Minneapolis: American Guidance Service, 1963. N I E , N. H., HULL.C. H.. JENKINS, J., STEINBRENNER, K., & BENT,D. H. SPSS: Statistical pachage for the social sciences. (2nd ed.) New York: McGraw-Hill, 1975. PIKULSKT. J. The validity of three measures of intelligence for disabled readers. Journal o f Educational Research, 1973, 67, 67-68, 80. SAITLER. J. Assessment of children's intelligence. Philadelphia: Saunders, 1974. SLOSSON.R. L. Slosson Intelligence Test for Children and Adults. New York: Slosson Educational Publ., 1963. VANCE.H. B., PRITCHARD,K. K., & WALLBROWN. F. H. Comparison of the WISC-R and PPVT for a group of mentally retarded students. Psychology in the Schools, 1978, 15, 244-251. WECHSLER,D. Manual for the Wechsler Intelligence Scale for Children. New York: Psychological Corp., 1949. WECHSLER,D. Manual for the IVechsler Intelligence Scale for Children-Revised. New York: Psychological Corp., 1974.

Accepted March 9, 1979.

Correlations of the Wechsler Intelligence Scale for Children-Revised, Peabody Picture Vocabulary Test, and Slosson Intelligence Test for a group of learning disabled students.

Psychological Reports, 1979, 44, 735-738. @ Psychological Reports 1979 CORRELATIONS OF THE WECHSLER INTELLIGENCE SCALE FOR CHILDREN-REVISED, PEABODY...
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