Psychology in the Schools Volume 20. Januarv. 1983

EFFECTIVENESS OF THE PPVT-R FOR SCREENING GIFTED STUDENTS DAN WRIGHT

Ralston Public Schools

The PPVT-R and the WISC-R were administered to a sample of 35 students, grades 1 through 8, who were nominated for possible participation in gifted programming. The correlation between the PPVT-R and Full Scale IQ was .27, which probably was affected by the restricted range of ability assessed. The PPVT-R showed modest in- cremental effectiveness beyond informal referral procedures in predicting toward a WISC-R criterion score.

Citing improvements of the revised Peabody Picture Vocabulary Test (PPVT-R, Dunn & Dunn, 1981) over its predecessor, and based on the performance of a sample of gifted children on both editions of the instrument, Pedriana and Bracken (1982) have suggested that the new revision should be an effective instrument for screening gifted children. Much of the existing research literature, however, offers only tenuous support for such a recommendation. Although studies of concurrent validity with placement in- struments such as the Wechsler Intelligence Scale for Children-Revised (WISC-R, Wechsler, 1974) generally report correlations in the moderate range, it has been demonstrated in a variety of special populations that scores from the previous edition are not interchangeable with IQ scores (see Sattler, Bohanan, & Moore, 1980, for a study and review). Bracken and Prasse (1981) have reported low correlations of the new edition with IQ data in a sample of educable mentally retarded students, but maintain it may yet be useful as a screening instrument with that population. The purpose of the present study is to examine the effectiveness of the PPVT-R as a screening instrument for gifted children.

METHOD Subjects

The children were 35 students in grades 1 through 8 (17 boys, 18 girls; median age 10-9) who were referred by parents or teachers for possible participation in gifted programming because of outstanding academic achievement. All children were white and of middle socioeconomic background, and attended a small, urban school district in the Midwest. Procedure

Referred students were tested initially by one of four reading specialists using the PPVT-R. Two of the specialists employed Form L and two employed Form M, with the result that Form L was used in 18 cases and Form M in 17 cases. Regardless of scores obtained, the children were administered the WISC-R by one of two certified school psy- chologists within one to five weeks following. The criterion for participation in gifted programming was a Full Scale score on the WISC-R at or above the 98th percentile (i.e., 131 or above).

RESULTS AND DISCUSSION Means and standard deviations of standard scores on the WISC-R were: VIQ, 123.0

& 9.8; PIQ, 121.7 & 10.3; FSIQ, 125.1 & 9.0. For the PPVT-R, Forms L and M com-

Requests for reprints should be sent to Dan Wright, Ralston Public Schools, District No. 54, 8545 Park Drive, Ralston, NE 68 127-3690.

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26 PPVT-R for Gifed Screening

bined, the mean and standard deviation of standard scores were 118.9 & 12.0. Pearson product moment correlation of the PPVT-R with WISC-R VIQ, PIQ, and FSIQ yielded coefficients of .50, -. 12, and .27, respectively. The correlation of VIQ with PIQ was .23; this is considerably lower than the correlation of .67 between these two measures reported in the standardization sample, and testifies to the effects of restriction of range in the present sample.

In order to employ the PPVT-R as a screening measure, one must predict toward the inclusion criterion on the WISC-R. Although there are mathematical procedures for determining optimal cutoff scores (e.g., Darlington & Stauffer, 1966), examination of a scatterplot of test scores is a flexible and easily interpretable method. Having drawn a line to indicate the WISC-R criterion, one may manipulate a perpendicular line representing the PPVT-R cutoff while considering the resulting number of cases in each quadrant according to values associated with successes and errors in prediction. In the present sample, the optimal cutoff on the PPVT-R was determined in this fashion to be a standard score of 112, which resulted in the following prediction outcomes: 1 1 children who passed the PPVT-R cutoff and the WISC-R criterion; 15 children who passed the cutoff but failed the criterion; 0 children who failed the cutoff but passed the criterion; 9 children who failed both cutoff and criterion.

Optimal use of the PPVT-R as a screening measure in the present sample thus could have reduced the number of referrals for formal assessment by 26% (9 cases), and would have improved the success rate of formal assessments from 31% (1 1 out of 35 cases) to 42% ( 1 1 out of 26 cases). From a practical standpoint, the modest gains in accuracy from such a screening program would be almost equally offset by the time and expense in- volved in devoting certified personnel to screening. The PPVT-R appears to offer little in- cremental effectiveness as a screening measure when sample selection (such as produced by teacher referral and consideration of classroom achievement) restricts the range of ability assessed. Although it may be useful as a screening measure with a general popula- tion, present results suggest that even informal referral procedures seriously diminish its effectiveness.

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DARLINGTON, R . B., & STAUFFER, G. F.

DUNN, L. M., & DUNN, L. M . Guidance Service, 198 I .

PEDRIANA, A. J . , & BRACKEN, B. A . in the Schools, 1982, 19, 183-185.

SATTLER, J . M., BOHANAN, A. L., & MOORE, M. K. with reading disabilities. Psychology in the Schools, 1980, 17, 331-334.

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Comparison of the PPVT, PPVT-R, and intelligence tests used for the placement of black, white, and Hispanic EMR students. JournalofSchool Psychology, 1981,19,304-31 I ,

A method for choosing a cutting point on a test. Journal of Applied

Peabody Picture Vocabulary Test-Revised. Circle Pines, MN: American

Performance of gifted children on the PPVT and PPVT-R. Psychology

Relationship between PPVT and WISC-R in children

Wechsler Intelligence Scale for Children-Revised. New York: The Psychological Corpora-

Psychology, 1966, 50, 229-23 I .