Sorel Cahan

A Between-Grade-Levels Approach to the Investigation of the Absolute Effects of Schooling on Achievement

The universal nature of school attendance precludes the experimental investigation of the absolute effect of schooling on achievement. The available empirical evidence consists of the results of post hoc analyses of the within-grade-level relationship of students’ achievement to the quality and quantity of schooling. This paper suggests a between-grade-levels quasi-experimental approach to the investigation of school’s effect on achievement, involving the estimation of this effect by means of a regression discontinuity design. The paper presents the rationale underlying the suggested approach and demonstrates its application to the estimation of the effect of schooling at grade 2 on achievement in mathematics and reading comprehension.

The Kaufman Ability Battery for Children Mental Processing Scale: A Valid Measure of “Pure” Intelligence?

The Kaufman Ability Battery for Children (K-ABC) is predicated on the distinction between intelligence (measured by the Mental Processing scale) and achievement (measured by the Achievement scale). This article questions the validity of this distinction and the interpretation of the K-ABC’s Mental Processing score as a measure of “pure” intelligence, uncontaminated by schooling. Schooling was found to affect raw scores on all Mental Processing subtests in the Israeli standardization sample of the K-ABC. More-over, for five of the eight subtests, the effect of schooling exceeded the effect of age. No difference was found between the Mental Processing and Achievement scales in the relative magnitude of the age and schooling effects.

Significance Testing of Subtest Score Differences: The Case of Nonsignificant Results

Though the testing for the statistical significance of subtest score differences yields a considerable proportion of nonsignificant results (e.g., about two-thirds of the V-P IQ differences on the WISC-R, assuming α = .05), the interpretation of such results has been neglected. This paper examines the implications of the decision rule as they concern statistically nonsignificant results. The acceptance of the null hypothesis after a nonsignificant difference is shown to result in a noticeable proportion of both Type II and classification errors. Thus, in view of its low statistical power and the considerable proportion of classification errors involved, the widespread use of significance testing of subtest score differences is questioned; it cannot be justified in terms of a very extreme loss function, which emphasizes the minimization of the α-probability of Type I errors at the expense of the β-probability of Type II errors. Two other explanations for the universal acceptance of the significance testing of subtest score differences are suggested and critically examined.

Constancy of IQ scores among gifted children

In light of the outdatedness of empirical research on IQ constancy among gifted children, and with the aim of examining possible cross cultural differences, the present study investigated the issue within the Israeli context. Specifically, we analyzed the constancy of IQ scores on the WISC‐R test for 161 kindergarteners through fourth graders identified as gifted by the Jerusalem Psychological Service in 1981/82‐ 1983/84. Assessment of IQ constancy was based on a retest administered to subjects 1–4 years after the first test. Results showed that 86% of the children in the sample were defined as gifted also on retest. Mean absolute differences between testings ranged from 1/3 to 1/2 SD (5–8 IQ points) for Verbal, Performance and Full‐scale IQ scores, and from 1/2 to 3/4 SD for subtest scores. On the whole, Performance scores remained constant, while Verbal scores tended to decline. There were no consistent differences attributable to age of identification or measurement interval.

Schooling and the Development of Transitive Inference.

Because it is impossible to experiment with school attendance, the erect of formal education as opposed to chronological age on the development of transitive inference has never been investigated empirically. A recent quasi-experimental paradigm, which allows for disentangling the net erects of age and schooling, can help overcome this difficulty. The paradigm is applied to the estimation of the independent erects of age and schooling in Grades 5 and 6 on raw scores obtained in a 3-term series test. Results point to schooling as a major factor underlying the increase of scores as a function of age

Significance Testing of Subtest Score Differences: the Rules of the Game:

Significance testing is widely used as one way to evaluate subtest score differences. Nevertheless, misinterpretations of statistically significant differences are frequent, due to basic misunderstandings of the underlying model. This article reviews the significance testing model and discusses the interpretations and misinterpretations of statistically significant differences.

The Regression-Based Discrepancy Definition of Learning Disability: A Critical Appraisal

The regression-based discrepancy definition of learning disabilities has been suggested by Rutter and Yule as an improvement of the well-known and much criticized achievement–intelligence discrepancy definition, whereby the examinee’s predicted reading attainment is substituted for the intelligence score in the discrepancy expression. Even though the regression-based discrepancy definition has been with us for more than 30 years, critical examination of this approach is scarce. This article fills this lacuna by examining the implications of two variables in the model on the diagnosis of learning disabilities: (a) the effect of predictive validity on the proportion of examinees identified as learning disabled, and (b) the effect of the predictor’s identity on the identity of the examinees diagnosed with learning disabilities. Implications of these effects concerning the validity of the regression-based discrepancy model and of the results of its implementation are discussed.

Mind the Gap: Between-Group Differences and Fair Test Use

This paper integrates recent meta-analytical findings regarding group differences in job- and educational-related criteria and cognitive ability measures used as predictors in personnel selection and selection to higher education institutions. The findings suggest that cognitive ability measures reveal much higher group differences than the corresponding between-group differences in job- and educational-related criteria. One possible explanation for these differential gaps is that cognitive ability measures are objective and standardized while the typical measures used as job- and-educational related criteria are non-standardized subjective evaluations of job performance and academic achievement. While these findings are consistent with unbiased prediction or over-prediction for lower scoring groups, they imply that selection is biased against them. Implications and future research are discussed.

Cognitive gender differences among Israeli children

The study investigated gender differences among 11,000 Israeli children in Grades 4–6 with respect to verbal, spatial, and mathematical ability, as measured by 12 intelligence tests. Consistent differences in score variance were found across grades for 11 of the 12 tests. In each of these tests the variance for boys exceeded that for girls by 10%–20%. With respect to mean achievement, consistent cross-grade differences were found only for mathematical ability, where boys had the edge (about 0.20 SD). These findings diverge from those of recent American studies, which found no gender differences in any of these realms. Furthermore, they differ from the results of earlier Israeli studies in that the gender gap is limited to mathematical ability, and its size is much smaller. The revealed gender gap can be partially attributed to differences in response strategy: girls were found to be more likely to skip items for which they lack an answer (i.e., to take fewer risks in guessing). This implies that the performance of girls on intelligence tests will improve if they are encouraged to dare to guess.

Between-context variability of the effect of schooling on cognitive development: evidence from the Middle East

This study contributes to the investigation of the variability of the schooling effect on cognitive development between educational systems and its underlying factors, by focusing on 3 cases differing in the characteristics assumed to affect the magnitude of the schooling effect (the quality of the schooling and students’ mean ability to benefit from their schooling): the United Nations Relief and Works Agency (UNRWA) educational system in the Palestinian refugee camps in the West Bank and the 2 sectors of the Israeli educational system: the Jewish and Arab systems. Congruent with our expectations, the highest absolute and relative effects of schooling were found in the Israeli Jewish system. In contrast, the results obtained in the 2 Arab systems, namely, the higher schooling effect found in the poorer and more oppressed refugee camps of the West Bank, are surprising and require further investigation.