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Biomedical subjects

A B Silverstein

Publications and source records attributed to A B Silverstein.

At least 19 recordsLinked to original sources
PubMed1991

Reliability of score differences on Wechsler's intelligence scales.

Comparisons are made between the results given by two formulae for the reliability of the difference between an individual subtest score and the average subtest score on a scale to which that subtest belongs. For the WAIS-R and the WISC-R, the correct reliabilities reported here are appreciably higher than the incorrect reliabilities reported previously, and the apparent reversal of this result for the WPPSI is explained as an artifact. Even the correct reliabilities are very low, however, more than three-quarters of them below .70.

Child↗
PubMed1990

Notes on the reliability of Wechsler short forms.

Information is provided on the reliability of random short forms of Wechsler's intelligence scales and on the reliability of short forms that reduce the number of items within subtests rather than the number of subtests. The results demonstrate how much better than random the most reliable short forms of the scales are. They also show that reducing the number of items within subtests rather than the number of subtests exacts a steep price in reliability.

Humans↗
PubMed1990

Critique of a Doppelt-type short form of the WAIS-R.

The purpose of this article is to correct a number of errors in a study by Reynolds, Willson, and Clark (1983). The short form that they proposed, which consists of Information and Arithmetic from the Verbal Scale and Picture Completion and Block Design from the Performance Scale, is shown to be more reliable and more valid than they realized. A corrected table is presented for converting the sums of age-scaled scores on their short form to estimated Full Scale IQs.

Adolescent↗
PubMed1990

Update on the parallel analysis criterion for determining the number of principal components.

Recent developments in parallel analysis with unities in the diagonal are reviewed, and the application of the parallel analysis criterion is illustrated with three examples. It is shown that the results of various approaches do not always agree. Investigators are encouraged to employ the parallel analysis criterion, along with one or more other criteria, in deciding on the number of principal components.

Analysis of Variance↗
PubMed1989

Confidence intervals for test scores and significance tests for test score differences: a comparison of methods.

Two methods of setting confidence intervals for test scores and testing the significance of test score differences are compared with respect to their simplicity and the similarity of their results. The conventional method, which is based on obtained scores, is unquestionably simpler than the technically correct method, which is based on estimated true scores, but the two methods may give rather different results, depending on the reliability coefficient(s) of the test(s), the distance of the score(s) from the mean, and the confidence or significance level. The standardization data for the WISC-R are used to illustrate the effects of those factors.

Child↗
PubMed1989

Reliability and abnormality of scaled-score ranges.

The distinction between the reliability (statistical significance) and the abnormality (unusualness) of test score differences is shown to apply equally to a common index of subtest scatter, the scaled-score range. The evaluation of scaled-score ranges on the WISC-R is used as an illustrative example.

Child↗
PubMed1989

Agreement between a short form and the full scale as a function of the correlation between them.

Much current research considers both correlational data and data on agreement in evaluating the usefulness of short forms of Wechsler's intelligence scales. It is demonstrated that when chance is excluded and disagreements are suitably weighted, the agreement between a short form and the Full Scale is simply an approximation to the correlation between them. Thus, the correlation itself should be the primary consideration in evaluating the usefulness of a short form.

Child↗
PubMed1989

On the use of the WISC-R supplementary subtests as alternates.

If a regularly administered WISC-R subtest cannot be administered properly or is invalidated, the manual suggests that a supplementary subtest, either Digit Span or Mazes, can serve as a substitute, but perhaps prorating the sum of scaled scores on the remaining subtests would be better. Data from the WISC-R standardization sample were analyzed to investigate the psychometric properties of these two variants of the standard procedure. Proration consistently resulted in higher validities (i.e., correlations between scores on the variant Verbal, Performance, or Full Scale and scores on the corresponding original scale), whereas substitution almost as consistently resulted in higher reliabilities, but in both cases the differences were small. Examiners may decide for themselves whether or not to use the supplementary subtests as alternates.

Child↗
PubMed1989

A cluster analysis of institutionalized mentally retarded individuals.

The scores of two samples of 200 subjects each on five factors of a measure of adaptive behavior were subjected to cluster analysis using two hierarchical agglomerative clustering methods. Three clusters were found that proved stable across clustering methods, subject samples, and time points 3 years apart. In addition, cluster membership was shown to be meaningfully associated with a number of demographic characteristics and neurological and sensory handicaps. The three-cluster solution thus possesses some desirable features, but its practical utility remains to be demonstrated.

Activities of Daily Living↗
PubMed1988

Effects of age on the adaptive behavior of institutionalized and noninstitutionalized individuals with Down syndrome.

The effects of age on the adaptive behavior of individuals with Down syndrome and matched individuals in other diagnostic categories were compared in three studies. The only study that provided evidence of a decline in competence among older individuals with Down syndrome was the one study in which the oldest age category was 60 years and over. In that study, a significant Age X Diagnosis interaction was found for the Motor Development factor of the Client Development Evaluation Report, reflecting a sharp drop in the scores of some of the oldest subjects with Down syndrome. These results resemble those of other recent research in two respects: the age at which the decline in competence occurred and the nature of that decline.

Activities of Daily Living↗
PubMed1987

Multidimensional scaling vs. factor analysis of Wechsler's intelligence scales.

The relations between principal component and principal factor analysis, on the one hand, and metric and nonmetric multidimensional scaling, on the other, were explored by applying all four methods to the standardization data for the WAIS-R, the WISC-R, and the WPPSI. For each of the instruments, the first component/factor was a general one that had no counterpart in the two scaling dimensions. The second component/factor and the first scaling dimension differentiated the Verbal from the Performance subtests, whereas the third component/factor and the second scaling dimension appeared to represent what has been called Freedom from Distractibility. The tendency of multidimensional scaling to remove the first general component/factor may be an undesirable feature of that method for investigating structure in the area of human abilities.

Factor Analysis, Statistical↗
PubMed1987

Two indices of subtest scatter on Wechsler's Intelligence Scales: estimated vs. empirical values.

Previous research on the scaled-score range and the number of deviant subtest scores on the WISC-R and the WPPSI has produced surprising results: Normal children exhibited much more scatter than most clinicians probably realized. Yet, in principle, these results were predictable from a knowledge of the statistical properties of scaled scores. Procedures for evaluating the abnormality of the two indices of scatter are presented and their accuracy checked against the actual distributions of the indices for the two standardization samples. The findings suggest that the procedures are sufficiently accurate for most clinical applications, which supports their use when the actual distributions of the indices are unknown.

Humans↗
PubMed1987

Unusual test score combinations and unusual test score differences.

Vocabulary and Abstraction scores on the Shipley Institute of Living Scale are used to illustrate the relation between unusual test score combinations and unusual test score differences. It is demonstrated that a combination of two scores can be unusual even though the corresponding difference is not and that a difference between two scores can be unusual even though the corresponding combination is not. Clinicians should be aware that although the two methods of pattern analysis generally will lead to the same conclusion, they need not do so.

Educational Measurement↗
PubMed1987

Accuracy of estimates of premorbid intelligence based on demographic variables.

Regression equations have been presented for estimating premorbid IQs on Wechsler's intelligence scales, using the demographic variables employed to stratify the various standardization samples as predictors. The accuracy of the resulting estimates for classifying patients into Wechsler's seven IQ categories (from very superior to mentally retarded) was evaluated, and it was found that even the best estimates can be expected to misclassify more than half of all patients. Such estimates still can contribute to valid inferences about a patient's premorbid intelligence, but only when they are used in conjunction with information from other sources.

Demography↗