Diagnostic utility of the K-ABC and WISC-R/PIAT in determining severe discrepancy

The basic question addressed in this study was whether the discrepancies found between the Mental Processing Composite (ability component) and the Achievement subtests of the Kaufman Assessment Battery for Children (K-ABC) corresponded with the discrepancies found between the WISC-R Full Scale IQ and the PIAT subtests, or whether use of the K-ABC over the WISC-R and PIAT results in the identification of different students. The differences were evaluated using four standard score procedures for calculating a severe discrepancy. It was found that the K-ABC and WISC-R/PIAT approaches to the determination of a score difference resulted in the identification of different populations of students. The high average PIAT standard scores together with the lower subtest reliabilities appeared to be the primary source of disparity between the K-ABC and WISC-R/PIAT comparisons.     

Further investigation of the correlations among the WISC-R,PIAT, and DAM

The authors replicated a study (White, 1979) in which high correlations were obtained among the Wechsler Intelligence Scale for Children-Revised (WISC-R), the Peabody Individual Achievement Test (PIAT), and the Goodenough-Harris Draw-A-Man (DAM), and conclusions were drawn that all these instruments might not be necessary in the same test battery. The present study involved a larger sample (360 children). Much lower correlations among the instruments were obtained, although the pattern of correlation was similar. It was concluded that results of the White study may have overestimated the relationships between the variables because of factors unique to the sample. Test specificity appeared using the larger, normally distributed sample, suggesting a legitimate use of all three tests in a single battery.     

Investigations into the relationships of the WRAT,the PIAT,the SORT,and the WISC-R in low-functioning referrals

Research involving standardized reading achievement tests has been widespread, but there has been little investigation into the relationships among the more widely used tests of reading achievement. In the present study, the Reading subtest of the WRAT, the Reading Comprehension subtest of the PIAT, and the SORT were compared with each other and with the WISC-R. Results showed a high correlation between the WRAT and the PIAT, a moderately high correlation between the SORT and the PIAT, and a very low correlation between the SORT and the WRAT. The WRAT and the PIAT had higher correlations with the various components of the WISC-R than did the SORT. These findings imply that the WRAT and the PIAT measure essentially the same dimension of reading achievement, possibly verbal fluency, but that the SORT is measuring a different dimension, one that is also tapped to some extent by the PIAT.     

Predictors of ability-achievement discrepancies in children referred for psychoeducational evaluation

The present study evaluated a school district's psychoeducational screening program to determine the best predictors of two difference score variables: (a) WISC-R FSIQ – PIAT reading recognition score and (b) WISC-R FSIQ – PIAT math score. The study also investigated the merit of using scores from a group-administered achievement test (CAT) as predictors. Subjects were 61 first through fifth graders initially referred for testing from 1982–1984. Multiple regression analyses indicated: (a) for reading, the SIQ score and the PPVT-R – CAT reading difference score were significant predictors, together accounting for 27% of the variance, and (b) for math, the PPVT-R score accounted for 28% of the variance, with additional variables producing nonsignificant increments. Results suggest that CAT scores may prove useful predictors when combined with screening IQ tests to form difference scores.     

The WISC-R as a predictor of achievement

This study investigated the validity of the WISC-R IQs as predictors of achievement as measured by the PIAT. Both tests were administered to 188 children referred to the author because of learning problems. Regression analyses were run with each of the PIAT subtests and the total score as criteria and the WISC-R IQs as predictors. Each of the IQs was a significant predictor of each of the PIAT subtests, but the Verbal IQ predicted best. Regression equations were provided and several indications of the importance of the results were presented.     

Factor structure of intellectual and achievement measures for learning disabled children

The purpose of this study was to explore the factor structure of intelligence and achievement for learning disabled children. WISC-R, PIAT, and WRAT scores of 183 male, learning disabled students were factor analyzed. A factor structure was obtained. The factors were identified as: (a) language achievement, (b) perceptual organization, (c) verbal educative, and (d) mathematical achievement. These findings suggest that intelligence and achievement are composed of similar traits and skills. Therefore, comparison of individual achievement test scores with traditional Verbal, Performance, or Full Scale intelligence for learning disabled children may not be logical, since analysis of these tests reveals factorially complex skills.     

Determining basals for the peabody individual achievement test

The appropriateness of the starting points for PIAT subtests as suggested by the test authors was investigated. For a sample of 113 subjects with an average WISC-R Full Scale IQ of 98, there was an average difference of nearly 8 points between the suggested starting points for the Mathematics subtest and the actual basals. The difference between suggested starting points and basals for the other subtests ranged from 8 to 12 points. It was suggested that the PIAT user start each subtest approximately 8 items below that suggested by the Manual.     

Factor structure of the Wechsler Intelligence Scale for Children-Revised,Peabody Picture Vocabulary Test,and Peabody Individual Achievement Test in a psychiatric sample

This study analyzed the factor structure of the Wechsler Intelligence Scale for Children-Revised (WISC-R), the Peabody Picture Vocabulary Test (PPVT), and the Peabody Individual Achievement Test (PIAT) in a psychiatric sample that ranged in age from 6 to 16 years (mean age = 11.1 years; SD = 3.0). The resultant factor structure of this sample was compared with patterns reported on normal and learning-disabled children. The subjects were 329 children under inpatient and outpatient care who had been referred for emotional disturbances. The results were similar to previous factor analytic studies of the WISC-R and PIAT, showing four factors: Verbal Comprehension, Verbal Achievement, Perceptual Organization, and Number Facility. The implications for the interpretation of these tests in a psychiatric sample and the appropriateness of a maximum likelihood technique in analysis of psychometric data are discussed.     

A comparison of the peabody individual achievement test,the metropolitan achievement test,and the otis-lennon mental ability test

In order to clarify the concurrent validity of the Peabody Individual Achievement Test (PIAT) and the Metropolitan Achievement Test (MAT), product-moment correlations were computed for all subscores and total scores for 26 normal-range public school third-grade girls and boys. The reading comprehension subtests correlated.81, spelling.88, and PIAT Mathematics with MAT Total Math.64. Correlations were computed for the Otis-Lennon Mental Ability Test and the PIAT General Information subtest as.77, and the Otis-Lennon and the PIAT Total Test scores as.79. Concurrent validity of the PIAT with both tests is tentatively considered adequate except in the area of mathematics, in which the PIAT, relative to the MAT, appears to be reflecting ability to handle math concepts (.68) more accurately than math computation (.41) or math problem solving (.56). Correlations with IQ partialed out suggest the PIAT Total Test, and PIAT and MAT reading and spelling measures, are relatively uninfluenced by IQ variations, whereas with IQ held constant, the weak positive correlations between the PIAT and MAT math subtests became essentially random relationships.     

Matched pair comparison of WISC and WISC-R scores

Both the WISC and the WISC-R were administered to 54 children, with one half taking the WISC first and the other 27 taking the WISC-R first. Differences between mean subtest scaled scores and mean IQs were found to be influenced by the sequence of the tests, although all mean scores were higher on the second test when the WISC-R was given first. Data were presented suggesting the WISC-R given first tends to raise WISC scores, and WISC given first yields scores on the WISC-R which are essentially similar, effectively counsteracting the more “difficult” scoring for the WISC-R.     

Factor analysis of WISC-R scores for children identified as learning disabled,educable mentally impaired,and emotionally impaired

The WISC-R scores for groups of children identified by school personnel as needing special education services were factor analyzed according to type of classification. WISC-R factor loadings were obtained for the scores of children labeled Learning Disabled, Educable Mentally Impaired, and Emotionally Impaired, as well as groups labeled Other and None. Overall, results show the WISC-R to be factorially similar for all groups, with two principal factors emerging which correspond to the Verbal-Performance structure of the test. Significance tests among mean scale scores and IQ scores yielded few meaningful differences across groups.     

WISC-R: The first five years

Since its introduction five years ago (1974), 113 articles or papers have appeared regarding the WISC-R, including empirical investigations of its nature, as well as its comparability with a variety of other measures of intelligence and achievement, including the WISC. While not all this research has been carefully done, two general conclusions can be derived from the review. First, although the WISC-R involves modification in administration, design, and presentation of items, as well as a complete restandardization, the literature substantially suggests that it remains very similar in nature to its predecessor, the WISC. Investigations of factor analytic structures, standard errors, reliability coefficients, and subtest intercorrelations support the conclusion that individuals perform on the WISC-R largely the same as they do on the WISC. The second conclusion points out (with few exceptions): consistently lower scores were obtained on the WISC-R than on several other measures, including the WISC, the WAIS, the Slosson Intelligence Test, the Peabody Picture Vocabulary Test, and the Stanford Binet, which was revised shortly before the WISC. These lower scores on the WISC-R may be due to a variety of influences, including examiner variance, an artifact of design leading to inflated scores on the WISC, and finally and most obviously, the restandardization of the scale. The amount of literature that has appeared over the five-year period suggests that practitioners and researchers are as interested in learning about the WISC-R as they were about the WISC. Despite this fact and the conclusion that the WISC and WISC-R are substantially similar, the present authors encourage caution in the overgeneralization of findings until additional literature develops.     

Comparison of the PPVT-R and WISC-R: A validation study with second-grade students

The present investigation compared the PPVT-R/WISC-R scores of a “normal” or “nonexceptional population,” as well as whether prior administration of either of these instruments affected scores on the other. Forty public school second-grade students served as subjects and were randomly assigned to one of four groups, with the order of test administrations determined by group assignment: WISC-R/PPVT-R (Form L): WISC-R/PPVT-R (Form M); PPVT-R (Form L)/WISC-R; PPVT-R (Form M)/WISC-R. The results indecate that, as with exceptional populations, normal school children tend to score lower on the PPVT-R than on the WISC-R. Scores from these two tests are moderately correlated, and prior adminstration of one of the instruments does not appear to alter scores on the other. Implications for practice are discussed.     

The use of Wechsler Scales in the assessment of Native Americans of the Columbia River Basin

Native American secondary students from the Columbia Basin were found to have significant Verbal-Performance discrepancies on the WISC-R and WAIS. Mean Verbal scores were significantly below the normative mean, while Performance scores were at, or above, the normative means. These findings substantiated research with other Native American groups. Also, the Verbal and Performance scales correlated so low as to preclude the Full Scale from being an accurate representation of the “g” factor of intelligence. Further, the predictive validity of the WISC-R and the WAIS for reading and math achievement was found to be at variance with the standardization group.     

Interpretation of the PPVT-R: A pure measure of verbal comprehension?

The present study examined WISC-R scale, factor, and subtest scores in relationship to PPVT-R standard scores in order to test hypotheses regarding abilities measured by the PPVT-R. For a naturally occurring sample of rural children referred for assessment (N = 51), the results of direct and stepwise regression analyses indicated that, while verbal comprehension abilities may contribute most to successful performance on the PPVT-R, perceptual organization abilities also play a significant though less substantial role in the child's performance on the PPVT-R. While Vocabulary scaled scores accounted for 63% of the variance, addition of Object Assembly and Picture Arrangement scaled scores accounted for an additional 11% of the observed variance in PPVT-R performance. Students for whom the PPVT-R overestimated WISC-R Full Scale performance differed significantly from students for whom the PPVT-R underestimated their WISC-R performance only on the WISC-R Arithmetic subtest. Implications for interpretation of the PPVT-R are discussed.     

A comparison of the PIAT and WRAT: A closer look

A sample of 46 white fourth-grade pupils was administered the PPVT, WRAT, and PIAT, except for PIAT Reading Comprehension and General Information. Subjects were selected randomly from those pupils whom classroom teachers judged to be doing at least average academic work. Mean grade equivalents, as well as intercorrelations, were examined for PIAT and WRAT subtests. No sex differences were found for PPVT IQ, age, or most achievement scores. Mean grade equivalents generally ranged between the sixth-and seventh-grade levels. Nearly all PIAT-WRAT intercorrelations were positive and significant, and highest for the similarly labelled subtests. Substantial differences were noted in mean grade equivalents. WRAT Reading and Spelling exceeded their PIAT counterparts by approximately one grade level. In contrast, PIAT Mathematics exceeded WRAT Arithmetic by more than one grade level. The possible effects of differences in item content and task structures on performance were discussed. Implications for practitioners involved in psychoeducational evaluations were considered.     

A comparison of learning disabled college students' achievement from WRAT and PIAT grade,standard, and subtest scores

Although there have been a number of studies that compared the test results of the Wide Range Achievement Test (WRAT) and the Peabody Individual Achievement Test (PIAT), none had been accomplished with a group of college-aged learning disabled students. Indeed, few researchers had investigated populations over 16 years of age, and none had compared grade scores and standard scores with appropriate subtest scores as derived from these two instruments. With the recent emphasis on postsecondary education for the learning disabled, it is deemed critical that researchers should develop a data base for study of this population. The current research demonstrated that although both tests purport to measure academic achievement in reading, spelling, and arthmetic, in reality, significantly different scores are derived when WRAT (1965, 1978) norms are compared to PIAT (1970) norms as stated in grade scores and standard scores. These significant differences in the grade and standard scores clearly indicate that the WRAT and the PIAT, particularly in regard to arthmetic and to a lesser degree to reading, are not interchangeable instruments of academic achievement.     

The development of cutoff scores on a WISC-R in the multidimensional assessment of gifted children

The summed scores of the WISC-R dyad, Vocabulary and Block Design, were cross-tabulated with full scale WISC-R scores for 249 children referred to a gifted program. The initial results indicated that the Vocabulary-Block Design dyad could be a useful tool in predicting full scale IQ for some children and thus leave time available for other types of assessment of students.     

A comparison between the WISC and WISC-R among educable mentally retarded students

The study compared differences and similarities between WISC and WISC-R scores for 48 ten- and thirteen-year-old EMR students, who were matched according to sex and race. The WISC-R yielded significantly lower VS, PS, and FS IQ scores than the WISC for this predominantly rural Georgia population. The FS IQ scores from the WISC-R averaged 7.5 points lower than the WISC FS IQs, with similar differences noted for VS and PS scores. There was no significant difference in FS IQs between the two age groups. Results suggest that many children classified as “Borderline” or slightly above by the WISC will be classified as “Mentally Deficient” by the WISC-R.     

Can ability-achievement regression to the mean account for MDT discretionary decisions?

The test scores of 153 referred students who received inconsistent placements according to California's discrepancy criterion, which does not take regression into account (standard score distribution procedure), were reanalyzed using a procedure that accounts for regression. Students involved in these MDT discretionary decisions were placed into one of three groups: ineligible (originally met discrepancy criterion, but not placed), resource class (originally did not meet discrepancy criterion, but placed in a less restrictive pull-out program), and special day class (originally did not meet discrepancy criterion, but placed in a more restrictive, essentially full-time special education class). All of these placements were inconsistent with the nonregressed ability-achievement discrepancy criterion the MDTs used at the time of the IEP meeting. To evaluate how many of these students could be considered to be underachieving when regression is considered, regressed discrepancy scores were computed using the students' scores on the WISC-R and one or more of the following achievement tests: WRAT, PIAT, and W-J. Regression “accounted” for a significant proportion of the inconsistent placements in all three groups: ineligible (25.0%), resource class (31.5%), and special day class (46.9%). Implications for professional practice and public policy are discussed.