PsychologicalReports, 1992, 70, 27-30.
O Psychological Reports 1992
CORRELATIONS FOR WECHSLER INTELLIGENCE SCALE FOR CHILDREN-REVISED AND THE WECHSLER PRESCHOOL AND PRIMARY SCALE OF INTELLIGENCE FOR IRANIAN CHILDREN ' SIMA SHAHIM Shiraz Universio Summary.-This study focused on the relationship between the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) given to 40 6-yr.-old Iranian children. Pearson correlations between the WISC-R and the WPPSI IQs and between scaled scores on the corresponding subtests were significant. The comparison of mean IQs and scaled scores indicates that the WISC-R yielded a significantly higher Verbal IQ and higher scores on Information, Vocabulary, Comprehension, and Picture Completion than the WPPSI. The mean difference between corresponding Verbal and Full Scale IQs was not significant. These results suggest that scores on the two instruments correlated well for these 6-yr.-old Iranian children and the content on which IQs for the recently restandardized WISC-R and WPPSI are based are related.
The Wechsler Intelligence Scale for Children-Revised has been recently standardized in Iran (Shahim, 1990). The WISC-R was restandardized on a representative sample of 1400 children ages 6 to 13 years who were stratified on the basis of age, sex, and occupation of father according to the 1986 census of Iran. The technical manual of the WISC-R-(Wechsler, 1974) included Pearson correlations between the WISC-R and WPPSI (Wechsler, 1967) scaled scores and IQs for children 6.0 to 6.5 yr. old, the WISC-R and WPPSI overlap at this age. Wechsler reported high correlations between the corresponding Verbal IQs, Performance IQs, and Full Scale IQs. The mean IQs yielded by the WPPSI are reported as slightly higher than the corresponding WISC-R IQs (Wechsler, 1974). The purpose of the present study was to ascertain whether similar correlations exist between the restandardized WISC-R (Shahim, 1990) and the restandardized WPPSI (Razavieh & Shahim, 1990) for Iranian children 6.1 to 6.5 yr. old.
Subjects The subjects were 40 kindergarten and first grade children (20 boys and 20 girls) from ages 6.1 to 6.5 yr., with a mean age of 6.2. The subjects were 'The author is indebted to the Research Council of Shiraz University for supporting this study. Address correspondence and requests for reprints to the author, Department of Special Education, College of Education, Shiraz University, Shiraz, Iran.
28
S. SHAHIM
selected on the same stratification variables used to select the standardization sample. Procedure The two instruments were administered in a counterbalanced order by a female examiner with adequate training. The 12 WISC-R subtests and the ten WPPSI subtests were administered to each subject. The time interval between administration of the scales ranged from 29 to 64 days, the mean interval was 51 davs. The means and standard deviations of the scaled scores and IQs on the WISC-R and WPPSI subtests were calculated. Pearson product-moment correlations of scaled scores and IQs on the WISC-R with the corresponding scaled scores and IQs yielded by the WPPSI were obtained. The significance of the differences between the means of WPPSI and WISC-R IQs and between the means of corresponding subtests was assessed by Student's t for correlated measures.
RESULTSAND DISCUSSION The correlations between WISC-R and WPPSI IQs are shown in Table 1. The WISC-R Full Scale IQs showed a high correlation of .85 with the WPPSI Full Scale IQs; similar correlations of .84 and .74 were obtained for IQs on the two Verbal Scales and between the two Performance Scales also. The magnitudes of these correlations are comparable to those reported by Wechsler (1974). TABLE 1 PEARSON COEFFICIENTS BETWEEN WISC-R WISC-R Verbal IQ Performance IQ Full Scale IQ
Verbal IQ 34' .58* .76*
AND
WPPSI IQs (N= 40)
WPPSI Performance IQ .66* .74* .75*
Full Scale IQ .85* .74* .85*
To assess more completely the comparability of the WISC-R and WPPSI scaled scores, Pearson product-moment correlations between the WISC-R and WPPSI subtests were obtained. The correlations for scaled scores on the corresponding subtests ranged from .42 for Block Design to .77 for Mazes (Table 2). All correlations were statistically significant. These findings suggest that the content of the corresponding subtests are similar. Descriptive statistics and two-tailed t values for scaled scores on subtests and IQs for scales of both instruments are presented in Table 3 . Comparison of mean IQs of the WPPSI and the WISC-R scales showed there were differences of 1 to 4 I Q points between the corresponding IQs. The two-tailed
29
IRANIAN PRESCHOOLERS' WECHSLER SCORES
TABLE 2 P ~ S OCOEFFICIENTS N BETWEENCORRESPONDING SCALEDSCORES ON WISC-R AND WPPSI SLTBTESTS Verbal Subtests Information
Performance Subtests
r
Animal House-Coding
.46* .65t .59t .51t .65t .45*
Vocabulary
Arithmetic Similarities Comprehension Sentences-Digit Span
Picture Completion Mazes Block Design
r
.51t .65t .77t .42'
*p
O Psychological Reports 1992
CORRELATIONS FOR WECHSLER INTELLIGENCE SCALE FOR CHILDREN-REVISED AND THE WECHSLER PRESCHOOL AND PRIMARY SCALE OF INTELLIGENCE FOR IRANIAN CHILDREN ' SIMA SHAHIM Shiraz Universio Summary.-This study focused on the relationship between the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) given to 40 6-yr.-old Iranian children. Pearson correlations between the WISC-R and the WPPSI IQs and between scaled scores on the corresponding subtests were significant. The comparison of mean IQs and scaled scores indicates that the WISC-R yielded a significantly higher Verbal IQ and higher scores on Information, Vocabulary, Comprehension, and Picture Completion than the WPPSI. The mean difference between corresponding Verbal and Full Scale IQs was not significant. These results suggest that scores on the two instruments correlated well for these 6-yr.-old Iranian children and the content on which IQs for the recently restandardized WISC-R and WPPSI are based are related.
The Wechsler Intelligence Scale for Children-Revised has been recently standardized in Iran (Shahim, 1990). The WISC-R was restandardized on a representative sample of 1400 children ages 6 to 13 years who were stratified on the basis of age, sex, and occupation of father according to the 1986 census of Iran. The technical manual of the WISC-R-(Wechsler, 1974) included Pearson correlations between the WISC-R and WPPSI (Wechsler, 1967) scaled scores and IQs for children 6.0 to 6.5 yr. old, the WISC-R and WPPSI overlap at this age. Wechsler reported high correlations between the corresponding Verbal IQs, Performance IQs, and Full Scale IQs. The mean IQs yielded by the WPPSI are reported as slightly higher than the corresponding WISC-R IQs (Wechsler, 1974). The purpose of the present study was to ascertain whether similar correlations exist between the restandardized WISC-R (Shahim, 1990) and the restandardized WPPSI (Razavieh & Shahim, 1990) for Iranian children 6.1 to 6.5 yr. old.
Subjects The subjects were 40 kindergarten and first grade children (20 boys and 20 girls) from ages 6.1 to 6.5 yr., with a mean age of 6.2. The subjects were 'The author is indebted to the Research Council of Shiraz University for supporting this study. Address correspondence and requests for reprints to the author, Department of Special Education, College of Education, Shiraz University, Shiraz, Iran.
28
S. SHAHIM
selected on the same stratification variables used to select the standardization sample. Procedure The two instruments were administered in a counterbalanced order by a female examiner with adequate training. The 12 WISC-R subtests and the ten WPPSI subtests were administered to each subject. The time interval between administration of the scales ranged from 29 to 64 days, the mean interval was 51 davs. The means and standard deviations of the scaled scores and IQs on the WISC-R and WPPSI subtests were calculated. Pearson product-moment correlations of scaled scores and IQs on the WISC-R with the corresponding scaled scores and IQs yielded by the WPPSI were obtained. The significance of the differences between the means of WPPSI and WISC-R IQs and between the means of corresponding subtests was assessed by Student's t for correlated measures.
RESULTSAND DISCUSSION The correlations between WISC-R and WPPSI IQs are shown in Table 1. The WISC-R Full Scale IQs showed a high correlation of .85 with the WPPSI Full Scale IQs; similar correlations of .84 and .74 were obtained for IQs on the two Verbal Scales and between the two Performance Scales also. The magnitudes of these correlations are comparable to those reported by Wechsler (1974). TABLE 1 PEARSON COEFFICIENTS BETWEEN WISC-R WISC-R Verbal IQ Performance IQ Full Scale IQ
Verbal IQ 34' .58* .76*
AND
WPPSI IQs (N= 40)
WPPSI Performance IQ .66* .74* .75*
Full Scale IQ .85* .74* .85*
To assess more completely the comparability of the WISC-R and WPPSI scaled scores, Pearson product-moment correlations between the WISC-R and WPPSI subtests were obtained. The correlations for scaled scores on the corresponding subtests ranged from .42 for Block Design to .77 for Mazes (Table 2). All correlations were statistically significant. These findings suggest that the content of the corresponding subtests are similar. Descriptive statistics and two-tailed t values for scaled scores on subtests and IQs for scales of both instruments are presented in Table 3 . Comparison of mean IQs of the WPPSI and the WISC-R scales showed there were differences of 1 to 4 I Q points between the corresponding IQs. The two-tailed
29
IRANIAN PRESCHOOLERS' WECHSLER SCORES
TABLE 2 P ~ S OCOEFFICIENTS N BETWEENCORRESPONDING SCALEDSCORES ON WISC-R AND WPPSI SLTBTESTS Verbal Subtests Information
Performance Subtests
r
Animal House-Coding
.46* .65t .59t .51t .65t .45*
Vocabulary
Arithmetic Similarities Comprehension Sentences-Digit Span
Picture Completion Mazes Block Design
r
.51t .65t .77t .42'
*p
