Psychological Reports, 1992, 71, 863-866.
O Psychological Reports 1992
A SHORT FORM O F T H E WECHSLER PRESCHOOL AND PRIMARY SCALE O F INTELLIGENCE FOR USE IN IRAN ' ASGHAR RAZAVIEH AND SIMA SHAHIM Shiraz Universio Summary.-Data from the standardization of the Wechsler Preschool and Primary Scale of Intelligence in Shiraz, Iran (193 girls, 203 boys 4 to 6.5 yr. old) were used to develop a short form. Four subtests (Vocabulary, Arithmetic, Picture Completion, and Block Design) were selected on the basis of their high correlations with Full Scale IQs. The validity coefficients were high and significant. The standard errors for the short form were 4.0 to 6.0 points. The short form classified correctly about 73% of the subjects by category of intelligence but tended to underestimate the IQs of subjects of high intelligence and to overestimate the IQs of subjects with low intelligence. Further work is required.
Much research has been performed with short forms of the Wechsler intelligence scales including the Wechsler Preschool and Primary Scale of Intelligence (2, 3, 5, 11, 12). Two basic approaches in designing these short forms have been item limitation or the Satz-Mogel-Yudin approach and subtest limitation or a combined approach ( 5 , 10). Item limitation, although advantageous for the purpose of a profile analysis, has been criticized for lowered reliabilities (2). Many recent studies, however, have concentrated on limitation of the subtests. Most of these studies have focused on two- and foursubtest short forms (4, 12). Tetrads have been reported to provide more adequate representation of the Full Scale 1Q than dyads (2, 5). Although the validity and usefulness of various short forms of the WPPSI have been demonstrated for use in the United States, little evidence is found in the literature on the validity of the short forms for societies of different cultural backgrounds. Therefore, the current study was designed with the aim of developing a short form of the WPPSI for use in Iran. The following three criteria from those suggested by Resnick and Entin (8) were applied. For the short forms to be considered valid: (a) the estimated IQs and the actual F d Scale IQs should be highly correlated, (b) the short form IQ classification and the Full Scale IQ classification should be highly congruent, and (c) the difference between means of the short form IQs and Full Scale IQs should not be significant. METHOD The data were the standardization data of the Wechsler Preschool and Primary Scale of Intelligence in Shiraz, Iran (7). The standardization sample had consisted of 193 girls and 203 boys from ages 4 to 6.5 yr. The sample was stratified for age, sex, and occupation of father according to the 1986 national census of Iran. 'The authors are indebted to the Research Council of Shiraz University for supporting this study. Correspondence and requests for reprints should be addressed to the authors at CoUege of Education, Shiraz University, Shiraz, Iran.
864
A. RAZAVIEH
& S. SHAHIM
The steps taken for the standardization of the WPPSI were the following. The subtests were first translated into Persian. Some of the items were eliminated for clear lack of congruence with Iranian culture. These items were replaced by similar items of apparently equal difficulty. A pilot study was conducted ro assess the applicabdity of the adapted items and to establish the difficulty for each item. The battery was administered by four trained female examiners.
RESULTSAND DISCUSSION The Pearson coefficients of correlation of all possible dyads with relevant IQs for ages 4, 5 , and 6 to 6% years were compared with relevant IQs for ages 4% and s1/2 years using the cross-validation method suggested and applied by Kaufman (3); see Tables 1 and 2. This comparison suggested that the two verbal subtests Vocabulary and Arithmetic had an average correlation coefficient of .91 with Verbal I Q , and the two performance subtests of Picture Completion and Block Design had an average correlation coefficient of .87 with Performance IQ. These subtests were selected for the short form because they had the highest correlations with the relevant IQs at all age levels. I n addition, the group of four tests had a reasonable length and formed a unit in which each test measured different mental functions. Verbal-numerical combination has frequently been shown to be an excellent preTABLE 1
Dyads
Verbal Dyads Information, Similarities Vocabulary, Arithmetic Information, Vocabulary Idormation. Arithmetic Information, Comprehension Vocabulary, SlmiIarities Comprehension, Similarities Arithmetic, Similarities Vocabulary, Comprehension Arithmetic, Comprehension Performance Dyads Picture Completion, Block Design Picture Completion, Geometric Design Animal House, Geometric Design Picture Completion, Maze Block Design, Geometric Design Animal House, Maze Animal House, Block Design Animal House, Picture Completion Maze, Block Design Maze, Geometric Design
865
IRANIAN SHORT-FORM WPPSI
dictor of achievement (3). According to the experience of the authors, the Vocabulary subtest selected for this short form is a good predictor of aptitude for Iranian children. Further, the Vocabulary subtest having undergone the greatest cultural revisions seemed to be culturally fair for measuring intelligence of Iranian children. Block Design and Picture Completion have been selected in other studies including Kaufman's (3) to take advantage of their different modes for responding and their clinical values. TABLE 2
Dyads
Mr
Age, yr.
Verbal Dyads Information, Comprehension Ar~rhmetic,Similarities Vocabulary, Arithmetic Ar~thmetic,Comprehension Information, Vocabulary Information, Arithmetic Information, Similarities Vocabulary, Similarities Comprehension, Similarities Vocabulary, Comprehension Performance Dyads Picture Completion, Block Design Animal House, Geometric Design Animal House, Block Design Maze, Block Design Animal House, Picture Completion Animal House, Maze Picture Completion, Geomeuic Design Picture Completion, Maze Block Design, Geometric Design Maze. Geometric Desien
4%
5 'h
.95 .91 .90 .92 .91 .88 .90 .87 .90 .91
.87 .92 .90 .84 .85 .88 .84 .87 .81
.91 .91 .90 .88 .88 .88 .87 .87 .87 .86
.90 .89 .87 .92 .85 .86 .86 .86 .80 .81
.92 .90 .91 .85 .90 .89 .90 .85 .91 .87
.9I .90 .89 .89 .88 .88 .88 .86 .86 .84
.84
The equation for converting the sum of the scaled scores on the short form to Full-Scale I Q equivalents was derived by applying the procedure suggested by Tellegen and Briggs (14). Average intercorrelations between subtests (7) were used to obtain the following conversion equation: Estimated IQ
=
1.56(sum of scaled scores) + 36.4
Since Tellegen and Briggs' method does not permit the calculation of standard error of estimate in the customary way (12), the method applied by Silverstein (13) was employed. The values of standard error of estimate were 5.2, 4.2, and 4.7 for the ages of 4, 5 , and 6 years. These results are comparable to those reported by Kaufman (3).
866
A. RAZAVIEH & S. SHAHIM
The validity coefficients using McNamar formula (6) for the age levels of 4, 4.5, 5, 5.5, and 6 years were .94, .96, .92, .95, and .96, respectively. These coefficients are higher than those reported in s i d a r studies i3, 5, 11) for WPPSI and WISC-R short forms. A comparison of the percentage of correct classification by IQs on the short form and standard form showed chat in 73% of the cases there is congruence in the classification of IQs. In the remaining 27% of the cases the classification deviated by only one category. A tendency was observed for the IQs obtained from the short form to regress toward the mean of the distribution. Therefore, the short form tended to underestimate the IQs of high and very high intelligence subjects by one category in 31.7% of the cases. It also tended to overestimate the IQs of subjects with IQs below 80 by one category for 88% of the cases. These results are comparable to those reported by Haynes and Atkinson (21, Ryan (9), and Haynes (1) when using WPPSI and WISC-R short forms. The difference between Estimated IQs and Full Scale IQs was not significant at any of the three age levels. The results suggest that this short form of the WPPSI yields high validity coefficients and the obtained standard errors of estimate are quite characteristic of the WPPSI short forms (3). The short form, although accurate in classifying intelligence categories in 73% of the cases, in remaining cases the obtained IQs were misclassified by one category for subjects of both high and of low intelligence. I t may be concluded that this short form could be used confidently for estimating the IQs of avenge individuals; however, caution is in order when screening subjects of low and high intelligence is the aim of applying this short form. REFERENCES 1. HAYNES,J. (1982) Validity of a WISC-R short form with male delinquents. Journal of Clinical Psychology, 38, 406-408. 2. HAYNES,J. I)., & ATKINSON,D. (1983) Validity of two WPPSI short forms in outpatient clinic settings. Journal of Clinical Psychology, 39, 961-964. 3. KAUFMAN,A. S. (1972) A short form of the Wechsler Preschool and Primary Scale of Intelligence. Journal of Consulting and Clinical Psychology, 39, 361-369. 4. KAUFMAN, A. S. (1977) Should short-form validity coefficients be corrected? Journal of Consulting and Clinical Psychology, 45, 1159-1160. 5. KING,J. D., & SMITH,R. A. (1972) Abbreviated forms of the Wechsler Preschool and Primary Scale of Intelligence for a kindergarten population. Psychological Reports, 30, 539-542. 6. MCNAMAR,Q. (1974) Correction to a correction formula. Journal of Consulting and Clinical Psychology, 42, 145-146. 7. RAZAVEH,A,, & SHAHIM,S. (1990) Translation, adaptation and standardization of the WPPSI i n Iran. Jotrrnal of Social Sciences and Humanities, Shiraz Univer., 10, 49-75. 8. RESNICK,R. J., & ENTIN,A. D. (1971) Is an abbreviated form of the WISC valid for Afro-American children? Journal of Consulting and Clinical Psychology, 36, 97-99. 9. RYAN,J. (1981) Clinical utility of a WISC-R short form. Journal of Clinical Psychology, 37. 389-391. 10. SAITLER,J. M. (1982) Assessment of children's intelligence. Boston, M A : Allyn & Bacon. 11. SILVERSTE~N, A. B. (1970) Reappraisal of the validity of a short form of Wechsler's scales. Psychological Reports, 26, 559-560. 12. SILVERSTEIN, A. B. (1983) Full Scale I Q equivalents for a two-subtest short form of the Wechsler Preschool and Primary Scale of Intelligence and the Wechsler Intelligence Scale for Children-Revised. Psychological Reports, 53, 16-18. 13. SILVERSTEIN, A. B. (1985) A formula for the standard error of estimate of deviation quotients on short forms of Wechsler scales. Journal of Clinical Psychology, 4 1 , 408-409. 14. TELLEGEN, A,, & BRIGGS,P F. (1967) Old wlne In new skins: grouping Wechsler subtests into new scales. Journal of Consulting Psycholosy, 3 1 , 499-506. Accepted September 4, 1992
O Psychological Reports 1992
A SHORT FORM O F T H E WECHSLER PRESCHOOL AND PRIMARY SCALE O F INTELLIGENCE FOR USE IN IRAN ' ASGHAR RAZAVIEH AND SIMA SHAHIM Shiraz Universio Summary.-Data from the standardization of the Wechsler Preschool and Primary Scale of Intelligence in Shiraz, Iran (193 girls, 203 boys 4 to 6.5 yr. old) were used to develop a short form. Four subtests (Vocabulary, Arithmetic, Picture Completion, and Block Design) were selected on the basis of their high correlations with Full Scale IQs. The validity coefficients were high and significant. The standard errors for the short form were 4.0 to 6.0 points. The short form classified correctly about 73% of the subjects by category of intelligence but tended to underestimate the IQs of subjects of high intelligence and to overestimate the IQs of subjects with low intelligence. Further work is required.
Much research has been performed with short forms of the Wechsler intelligence scales including the Wechsler Preschool and Primary Scale of Intelligence (2, 3, 5, 11, 12). Two basic approaches in designing these short forms have been item limitation or the Satz-Mogel-Yudin approach and subtest limitation or a combined approach ( 5 , 10). Item limitation, although advantageous for the purpose of a profile analysis, has been criticized for lowered reliabilities (2). Many recent studies, however, have concentrated on limitation of the subtests. Most of these studies have focused on two- and foursubtest short forms (4, 12). Tetrads have been reported to provide more adequate representation of the Full Scale 1Q than dyads (2, 5). Although the validity and usefulness of various short forms of the WPPSI have been demonstrated for use in the United States, little evidence is found in the literature on the validity of the short forms for societies of different cultural backgrounds. Therefore, the current study was designed with the aim of developing a short form of the WPPSI for use in Iran. The following three criteria from those suggested by Resnick and Entin (8) were applied. For the short forms to be considered valid: (a) the estimated IQs and the actual F d Scale IQs should be highly correlated, (b) the short form IQ classification and the Full Scale IQ classification should be highly congruent, and (c) the difference between means of the short form IQs and Full Scale IQs should not be significant. METHOD The data were the standardization data of the Wechsler Preschool and Primary Scale of Intelligence in Shiraz, Iran (7). The standardization sample had consisted of 193 girls and 203 boys from ages 4 to 6.5 yr. The sample was stratified for age, sex, and occupation of father according to the 1986 national census of Iran. 'The authors are indebted to the Research Council of Shiraz University for supporting this study. Correspondence and requests for reprints should be addressed to the authors at CoUege of Education, Shiraz University, Shiraz, Iran.
864
A. RAZAVIEH
& S. SHAHIM
The steps taken for the standardization of the WPPSI were the following. The subtests were first translated into Persian. Some of the items were eliminated for clear lack of congruence with Iranian culture. These items were replaced by similar items of apparently equal difficulty. A pilot study was conducted ro assess the applicabdity of the adapted items and to establish the difficulty for each item. The battery was administered by four trained female examiners.
RESULTSAND DISCUSSION The Pearson coefficients of correlation of all possible dyads with relevant IQs for ages 4, 5 , and 6 to 6% years were compared with relevant IQs for ages 4% and s1/2 years using the cross-validation method suggested and applied by Kaufman (3); see Tables 1 and 2. This comparison suggested that the two verbal subtests Vocabulary and Arithmetic had an average correlation coefficient of .91 with Verbal I Q , and the two performance subtests of Picture Completion and Block Design had an average correlation coefficient of .87 with Performance IQ. These subtests were selected for the short form because they had the highest correlations with the relevant IQs at all age levels. I n addition, the group of four tests had a reasonable length and formed a unit in which each test measured different mental functions. Verbal-numerical combination has frequently been shown to be an excellent preTABLE 1
Dyads
Verbal Dyads Information, Similarities Vocabulary, Arithmetic Information, Vocabulary Idormation. Arithmetic Information, Comprehension Vocabulary, SlmiIarities Comprehension, Similarities Arithmetic, Similarities Vocabulary, Comprehension Arithmetic, Comprehension Performance Dyads Picture Completion, Block Design Picture Completion, Geometric Design Animal House, Geometric Design Picture Completion, Maze Block Design, Geometric Design Animal House, Maze Animal House, Block Design Animal House, Picture Completion Maze, Block Design Maze, Geometric Design
865
IRANIAN SHORT-FORM WPPSI
dictor of achievement (3). According to the experience of the authors, the Vocabulary subtest selected for this short form is a good predictor of aptitude for Iranian children. Further, the Vocabulary subtest having undergone the greatest cultural revisions seemed to be culturally fair for measuring intelligence of Iranian children. Block Design and Picture Completion have been selected in other studies including Kaufman's (3) to take advantage of their different modes for responding and their clinical values. TABLE 2
Dyads
Mr
Age, yr.
Verbal Dyads Information, Comprehension Ar~rhmetic,Similarities Vocabulary, Arithmetic Ar~thmetic,Comprehension Information, Vocabulary Information, Arithmetic Information, Similarities Vocabulary, Similarities Comprehension, Similarities Vocabulary, Comprehension Performance Dyads Picture Completion, Block Design Animal House, Geometric Design Animal House, Block Design Maze, Block Design Animal House, Picture Completion Animal House, Maze Picture Completion, Geomeuic Design Picture Completion, Maze Block Design, Geometric Design Maze. Geometric Desien
4%
5 'h
.95 .91 .90 .92 .91 .88 .90 .87 .90 .91
.87 .92 .90 .84 .85 .88 .84 .87 .81
.91 .91 .90 .88 .88 .88 .87 .87 .87 .86
.90 .89 .87 .92 .85 .86 .86 .86 .80 .81
.92 .90 .91 .85 .90 .89 .90 .85 .91 .87
.9I .90 .89 .89 .88 .88 .88 .86 .86 .84
.84
The equation for converting the sum of the scaled scores on the short form to Full-Scale I Q equivalents was derived by applying the procedure suggested by Tellegen and Briggs (14). Average intercorrelations between subtests (7) were used to obtain the following conversion equation: Estimated IQ
=
1.56(sum of scaled scores) + 36.4
Since Tellegen and Briggs' method does not permit the calculation of standard error of estimate in the customary way (12), the method applied by Silverstein (13) was employed. The values of standard error of estimate were 5.2, 4.2, and 4.7 for the ages of 4, 5 , and 6 years. These results are comparable to those reported by Kaufman (3).
866
A. RAZAVIEH & S. SHAHIM
The validity coefficients using McNamar formula (6) for the age levels of 4, 4.5, 5, 5.5, and 6 years were .94, .96, .92, .95, and .96, respectively. These coefficients are higher than those reported in s i d a r studies i3, 5, 11) for WPPSI and WISC-R short forms. A comparison of the percentage of correct classification by IQs on the short form and standard form showed chat in 73% of the cases there is congruence in the classification of IQs. In the remaining 27% of the cases the classification deviated by only one category. A tendency was observed for the IQs obtained from the short form to regress toward the mean of the distribution. Therefore, the short form tended to underestimate the IQs of high and very high intelligence subjects by one category in 31.7% of the cases. It also tended to overestimate the IQs of subjects with IQs below 80 by one category for 88% of the cases. These results are comparable to those reported by Haynes and Atkinson (21, Ryan (9), and Haynes (1) when using WPPSI and WISC-R short forms. The difference between Estimated IQs and Full Scale IQs was not significant at any of the three age levels. The results suggest that this short form of the WPPSI yields high validity coefficients and the obtained standard errors of estimate are quite characteristic of the WPPSI short forms (3). The short form, although accurate in classifying intelligence categories in 73% of the cases, in remaining cases the obtained IQs were misclassified by one category for subjects of both high and of low intelligence. I t may be concluded that this short form could be used confidently for estimating the IQs of avenge individuals; however, caution is in order when screening subjects of low and high intelligence is the aim of applying this short form. REFERENCES 1. HAYNES,J. (1982) Validity of a WISC-R short form with male delinquents. Journal of Clinical Psychology, 38, 406-408. 2. HAYNES,J. I)., & ATKINSON,D. (1983) Validity of two WPPSI short forms in outpatient clinic settings. Journal of Clinical Psychology, 39, 961-964. 3. KAUFMAN,A. S. (1972) A short form of the Wechsler Preschool and Primary Scale of Intelligence. Journal of Consulting and Clinical Psychology, 39, 361-369. 4. KAUFMAN, A. S. (1977) Should short-form validity coefficients be corrected? Journal of Consulting and Clinical Psychology, 45, 1159-1160. 5. KING,J. D., & SMITH,R. A. (1972) Abbreviated forms of the Wechsler Preschool and Primary Scale of Intelligence for a kindergarten population. Psychological Reports, 30, 539-542. 6. MCNAMAR,Q. (1974) Correction to a correction formula. Journal of Consulting and Clinical Psychology, 42, 145-146. 7. RAZAVEH,A,, & SHAHIM,S. (1990) Translation, adaptation and standardization of the WPPSI i n Iran. Jotrrnal of Social Sciences and Humanities, Shiraz Univer., 10, 49-75. 8. RESNICK,R. J., & ENTIN,A. D. (1971) Is an abbreviated form of the WISC valid for Afro-American children? Journal of Consulting and Clinical Psychology, 36, 97-99. 9. RYAN,J. (1981) Clinical utility of a WISC-R short form. Journal of Clinical Psychology, 37. 389-391. 10. SAITLER,J. M. (1982) Assessment of children's intelligence. Boston, M A : Allyn & Bacon. 11. SILVERSTE~N, A. B. (1970) Reappraisal of the validity of a short form of Wechsler's scales. Psychological Reports, 26, 559-560. 12. SILVERSTEIN, A. B. (1983) Full Scale I Q equivalents for a two-subtest short form of the Wechsler Preschool and Primary Scale of Intelligence and the Wechsler Intelligence Scale for Children-Revised. Psychological Reports, 53, 16-18. 13. SILVERSTEIN, A. B. (1985) A formula for the standard error of estimate of deviation quotients on short forms of Wechsler scales. Journal of Clinical Psychology, 4 1 , 408-409. 14. TELLEGEN, A,, & BRIGGS,P F. (1967) Old wlne In new skins: grouping Wechsler subtests into new scales. Journal of Consulting Psycholosy, 3 1 , 499-506. Accepted September 4, 1992
