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This study examined the applicability and measurement invariance of the bifactor model of the 10 Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) core subtests in groups of children and adolescents (age range from 6 to 16 years) with low (IQ ≤79; N = 229; % male = 75.9) and normal (IQ ≥80; N = 816; % male = 75.0) IQ scores. Results supported this model in both groups, and there was good support for measurement invariance for this model across these groups. For all participants together, the omega hierarchical and explained common variance (ECV) values were high for the general factor and low to negligible for the specific factors. Together, the findings favor the use of the Full Scale IQ (FSIQ) scores of the WISC-IV, but not the subscale index scores. (PsycINFO Database Record, ((c) 2017 APA, all rights reserved).)

Individual differences in attentional control involve the ability to voluntarily direct, shift, and sustain attention. In studies of the role of attentional control in emotional adjustment, social relationships, and vulnerability to the effects of stress, self-report questionnaires are commonly used to measure this construct. Yet, convincing evidence of the association between self-report scales and actual cognitive performance has not been demonstrated. Across 2 independent samples, we examined associations between self-reported attentional control (Attentional Control Scale; ACS), self-reported emotional adjustment, Five-Factor Model personality traits (NEO Personality Inventory-Revised) and performance measures of attentional control. Study 1 examined behavioral performance on the Attention Network Test (ANT; Fan, McCandliss, Sommer, Raz, & Posner, 2002) and the Modified Switching Task (MST; Suchy & Kosson, 2006) in a large sample (n = 315) of healthy young adults. Study 2 (n = 78) examined behavioral performance on standardized neuropsychological tests of attention, including Conner's Continuous Performance Test-II and subtests from the Wechsler Adult Intelligence Scales, Third Edition (WAIS-III; Psychological Corporation, 1997) and Delis-Kaplan Executive Function System (D-KEFS; Delis, Kaplan, & Kramer, 2001). Results indicated that the ACS was largely unrelated to behavioral performance measures of attentional control but was significantly associated with emotional adjustment, neuroticism, and conscientiousness. These findings suggest that although self-reported attentional control may be a useful construct, researchers using the ACS should exercise caution in interpreting it as a proxy for actual cognitive ability or performance. (PsycINFO Database Record, ((c) 2017 APA, all rights reserved).)

Assessment of measurement invariance across populations is essential for meaningful comparison of test scores, and is especially relevant where repeated measurements are required for educational assessment or clinical diagnosis. Establishing measurement invariance legitimizes the assumption that test scores reflect the same psychological trait in different populations or across different occasions. Examination of Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) U.S. standardization samples revealed that a first-order 5-factor measurement model was best fitting across 9 age groups from 16 years to 69 years. Strong metric invariance was found for 3 of 5 factors and partial intercept invariance for the remaining 2. Pairwise comparisons of adjacent age groups supported the inference that cognitive-trait group differences are manifested by group differences in the test scores. In educational and clinical settings these findings provide theoretical and empirical support to interpret changes in the index or subtest scores as reflecting changes in the corresponding cognitive abilities. Further, where clinically relevant, the subtest score composites can be used to compare changes in respective cognitive abilities. The model was supported in the Canadian standardization data with pooled age groups but the sample sizes were not adequate for detailed examination of separate age groups in the Canadian sample. (PsycINFO Database Record, ((c) 2016 APA, all rights reserved).)

The purpose of the present investigation was to conduct a meta-analysis of the literature on examiner errors for the Wechsler scales of intelligence. Results indicate that a mean of 99.7% of protocols contained at least 1 examiner error when studies that included a failure to record examinee responses as an error were combined and a mean of 41.2% of protocols contained at least 1 examiner error when studies that ignored errors of omission were combined. Furthermore, graduate student examiners were significantly more likely to make at least 1 error on Wechsler intelligence test protocols than psychologists. However, psychologists made significantly more errors per protocol than graduate student examiners regardless of the inclusion or exclusion of failure to record examinee responses as errors. On average, 73.1% of Full-Scale IQ (FSIQ) scores changed as a result of examiner errors, whereas 15.8%-77.3% of scores on the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), and Processing Speed Index changed as a result of examiner errors. In addition, results suggest that examiners tend to overestimate FSIQ scores and underestimate VCI scores. However, no strong pattern emerged for the PRI and WMI. It can be concluded that examiner errors occur frequently and impact index and FSIQ scores. Consequently, current estimates for the standard error of measurement of popular IQ tests may not adequately capture the variance due to the examiner., ((c) 2016 APA, all rights reserved).)

This study used estimated factor scores from a bifactor analysis of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) to examine the unique effects of its latent variables on academic achievement. In doing so, we addressed the potential limitation of multicollinearity in previous studies of the incremental validity of the WAIS-IV. First, factor scores representing psychometric g and 4 group factors representing the WAIS-IV index scales were computed from a bifactor model. Subtest and composite scores for the Wechsler Individual Achievement Test-Third Edition (WIAT-II) were then predicted from these estimated factor scores in simultaneous multiple regression. Results of this study only partially replicated the findings of previous research on the incremental validity of scores that can be derived from performance on the WAIS-IV. Although we found that psychometric g is the most important underlying construct measured by the WAIS-IV for the prediction of academic achievement in general, results indicated that the unique effect of Verbal Comprehension is also important for predicting achievement in reading, spelling, and oral communication skills. Based on these results, measures of both psychometric g and Verbal Comprehension could be cautiously interpreted when considering high school students' performance in these areas of achievement., ((c) 2015 APA, all rights reserved).)

Assessor bias variance exists for a psychological measure when some appreciable portion of the score variation that is assumed to reflect examinees' individual differences (i.e., the relevant phenomena in most psychological assessments) instead reflects differences among the examiners who perform the assessment. Ordinary test reliability estimates and standard errors of measurement do not inherently encompass assessor bias variance. This article reports on the application of multilevel linear modeling to examine the presence and extent of assessor bias in the administration of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) for a sample of 2,783 children evaluated by 448 regional school psychologists for high-stakes special education classification purposes. It was found that nearly all WISC-IV scores conveyed significant and nontrivial amounts of variation that had nothing to do with children's actual individual differences and that the Full Scale IQ and Verbal Comprehension Index scores evidenced quite substantial assessor bias. Implications are explored., (2014 APA)

In order to assess the degree of cognitive decline resulting from a pathological state, such as dementia, or from a normal aging process, it is necessary to know or to have a valid estimate of premorbid (or prior) cognitive ability. The National Adult Reading Test (NART; Nelson & Willison, 1991) and the Wechsler Test of Adult Reading (WTAR; Psychological Corporation, 2001) are 2 tests developed to estimate premorbid or prior ability. Due to the rarity of actual prior ability data, validation studies usually compare NART/WTAR performance with measures of current abilities in pathological and nonpathological groups. In this study, we validate the use of WTAR scores and extend the validation of the use of NART scores as estimates of prior ability, vis-à-vis the actual prior (childhood) cognitive ability. We do this in a large sample of healthy older people, the Lothian Birth Cohort 1936 (Deary, Gow, Pattie, & Starr, 2012; Deary et al., 2007). Both NART and WTAR scores were correlated with cognitive ability tested in childhood (r = .66-.68). Scores on both the NART and the WTAR had high stability over a period of 3 years in old age (r in excess of .90) and high interrater reliability. The NART accounted for more unique variance in childhood intelligence than did the WTAR., ((c) 2013 APA, all rights reserved.)

Global composites (e.g., IQs) calculated in intelligence tests are interpreted as indexes of the general factor of intelligence, or psychometric g. It is therefore important to understand the proportion of variance in those global composites that is explained by g. In this study, we calculated this value, referred to as hierarchical omega, using large-scale, nationally representative norming sample data from 3 popular individually administered tests of intelligence for children and adolescents. We also calculated the proportion of variance explained in the global composites by g and the group factors, referred to as omega total, or composite reliability, for comparison purposes. Within each battery, g was measured equally well. Using total sample data, we found that 82%-83% of the total test score variance was explained by g. The group factors were also measured in the global composites, with both g and group factors explaining 89%-91% of the total test score variance for the total samples. Global composites are primarily indexes of g, but the group factors, as a whole, also explain a meaningful amount of variance., ((c) 2013 APA, all rights reserved.)

The interpretation of the Wechsler Intelligence Scale for Children--Fourth Edition (WISC-IV) is based on a 4-factor model, which is only partially compatible with the mainstream Cattell-Horn-Carroll (CHC) model of intelligence measurement. The structure of cognitive batteries is frequently analyzed via exploratory factor analysis and/or confirmatory factor analysis. With classical confirmatory factor analysis, almost all cross-loadings between latent variables and measures are fixed to zero in order to allow the model to be identified. However, inappropriate zero cross-loadings can contribute to poor model fit, distorted factors, and biased factor correlations; most important, they do not necessarily faithfully reflect theory. To deal with these methodological and theoretical limitations, we used a new statistical approach, Bayesian structural equation modeling (BSEM), among a sample of 249 French-speaking Swiss children (8-12 years). With BSEM, zero-fixed cross-loadings between latent variables and measures are replaced by approximate zeros, based on informative, small-variance priors. Results indicated that a direct hierarchical CHC-based model with 5 factors plus a general intelligence factor better represented the structure of the WISC-IV than did the 4-factor structure and the higher order models. Because a direct hierarchical CHC model was more adequate, it was concluded that the general factor should be considered as a breadth rather than a superordinate factor. Because it was possible for us to estimate the influence of each of the latent variables on the 15 subtest scores, BSEM allowed improvement of the understanding of the structure of intelligence tests and the clinical interpretation of the subtest scores., (PsycINFO Database Record (c) 2013 APA, all rights reserved.)

D. Wechsler (2008b) reported confirmatory factor analyses (CFAs) with standardization data (ages 16-69 years) for 10 core and 5 supplemental subtests from the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). Analyses of the 15 subtests supported 4 hypothesized oblique factors (Verbal Comprehension, Working Memory, Perceptual Reasoning, and Processing Speed) but also revealed unexplained covariance between Block Design and Visual Puzzles (Perceptual Reasoning subtests). That covariance was not included in the final models. Instead, a path was added from Working Memory to Figure Weights (Perceptual Reasoning subtest) to improve fit and achieve a desired factor pattern. The present research with the same data (N = 1,800) showed that the path from Working Memory to Figure Weights increases the association between Working Memory and Matrix Reasoning. Specifying both paths improves model fit and largely eliminates unexplained covariance between Block Design and Visual Puzzles but with the undesirable consequence that Figure Weights and Matrix Reasoning are equally determined by Perceptual Reasoning and Working Memory. An alternative 4-factor model was proposed that explained theory-implied covariance between Block Design and Visual Puzzles and between Arithmetic and Figure Weights while maintaining compatibility with WAIS-IV Index structure. The proposed model compared favorably with a 5-factor model based on Cattell-Horn-Carroll theory. The present findings emphasize that covariance model comparisons should involve considerations of conceptual coherence and theoretical adherence in addition to statistical fit., ((c) 2012 APA, all rights reserved)

Normative comparisons are an integral component of neuropsychological test interpretation and provide the basis for an inference of abnormal function and impairment. In order to remedy a deficit of normative standards for a large number of neuropsychology tests, Mitrushina, Boone, Razani, and D'Elia (2005) used the meta-analysis of studies that incorporated normal volunteers to create a type of normative standard for many tests in neuropsychology that were not adequately normed in the past. The present study examined this method by contrasting meta-analysis norms of the Wechsler Adult Intelligence Scale-Revised (WAIS-R; Wechsler, 1981) with its published quota norms. The study examined 12 experimental studies of the WAIS-R that included normal, control volunteers (N = 2,147). These were combined by meta-analysis, and the summary scores were compared. The meta-analysis revealed a significant sampling bias with studies recruiting more White and higher educated respondents than indicated by the U.S. Census. This bias was successfully corrected using Monte Carlo simulation and adjustments for quota sampling. The corrections could be applied to all meta-analysis norms currently in use and bring them in line with the U.S. Census demographics.

The present study examined the factor structure of the Wechsler Adult Intelligence Scale--Fourth Edition (WAIS-IV; D. Wechsler, 2008a) standardization sample using exploratory factor analysis, multiple factor extraction criteria, and higher order exploratory factor analysis (J. Schmid & J. M. Leiman, 1957) not included in the WAIS-IV Technical and Interpretation Manual (D. Wechsler, 2008b). Results indicated that the WAIS-IV subtests were properly associated with the theoretically proposed first-order factors, but all but one factor-extraction criterion recommended extraction of one or two factors. Hierarchical exploratory analyses with the Schmid and Leiman procedure found that the second-order g factor accounted for large portions of total and common variance, whereas the four first-order factors accounted for small portions of total and common variance. It was concluded that the WAIS-IV provides strong measurement of general intelligence, and clinical interpretation should be primarily at that level.

The structure of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV; D. Wechsler, 2003a) was analyzed via confirmatory factor analysis among a national sample of 355 students referred for psychoeducational evaluation by 93 school psychologists from 35 states. The structure of the WISC-IV core battery was best represented by four first-order factors as per D. Wechsler (2003b), plus a general intelligence factor in a direct hierarchical model. The general factor was the predominate source of variation among WISC-IV subtests, accounting for 48% of the total variance and 75% of the common variance. The largest 1st-order factor, Processing Speed, only accounted for 6.1% total and 9.5% common variance. Given these explanatory contributions, recommendations favoring interpretation of the 1st-order factor scores over the general intelligence score appear to be misguided.

Low scores across a battery of tests are common in healthy people and vary by demographic characteristics. The purpose of the present article was to present the base rates of low scores for the Wechsler Intelligence Scale for Children, fourth edition (WISC-IV; D. Wechsler, 2003). Participants included 2,200 children and adolescents between 6 and 16 years of age from the WISC-IV U.S. standardization sample. Measures considered in the base rates analyses included the 10 core subtests and the 4 index scores. Analyses were conducted for the entire standardization sample as well as stratified by different classifications of intelligence and different years of parental education. In the total sample, it is uncommon to have 6 or more subtest scores or 2 or more Index scores

The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV; D. Wechsler, 2003a) is often utilized to assess children with traumatic brain injury (TBI), although little information is available regarding its psychometric properties in these children. The current study examined WISC-IV performance in a sample of 61 children with TBI. As compared to the standardization sample, results indicated that the TBI group exhibited relative deficits on all subtest and index scores, with the greatest deficits on the Processing Speed Index (PSI) and Coding subtest scores. However, the Perceptual Reasoning Index score was not uniquely sensitive to brain injury, and the Cognitive Processing Index score was less sensitive to TBI than the PSI score. Also, the PSI did not uniquely predict learning and memory abilities, as had been reported in previous studies of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; D. Wechsler, 1991). The present findings indicate substantive differences between the WISC-III and WISC-IV profiles of children with TBI., (PsycINFO Database Record (c) 2010 APA, all rights reserved.)

Published empirical evidence for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) does not address some essential questions pertaining to the applied practice of intellectual assessment. In this study, the structure and cross-age invariance of the latest WAIS-IV revision were examined to (a) elucidate the nature of the constructs measured and (b) determine whether the same constructs are measured across ages. Results suggest that a Cattell-Horn-Carroll (CHC)-inspired structure provides a better description of test performance than the published scoring structure does. Broad CHC abilities measured by the WAIS-IV include crystallized ability (Gc), fluid reasoning (Gf), visual processing (Gv), short-term memory (Gsm), and processing speed (Gs), although some of these abilities are measured more comprehensively than are others. Additionally, the WAIS-IV provides a measure of quantitative reasoning (QR). Results also suggest a lack of cross-age invariance resulting from age-related differences in factor loadings. Formulas for calculating CHC indexes and suggestions for interpretation are provided., (PsycINFO Database Record (c) 2010 APA, all rights reserved.)

In a cross-validation of results from L. O. Graue et al. (2007), standard psychological assessment instruments, as well as tests of neurocognitive and psychiatric feigning, were administered under standard instructions to 24 participants diagnosed with mild mental retardation (MR) and 10 demographically matched community volunteers (CVH). A 2nd group of 25 community volunteers was instructed to malinger MR (CVM) during testing. CVM participants obtained Wechsler Adult Intelligence Scale (3rd ed.; D. Wechsler, 1997) Full Scale Intelligence Quotient scores that were significantly lower than the demographically similar CVH group but comparable to the MR group, suggesting that CVM subjects feigned cognitive impairment. On the basis of standard cutting scores from test manuals or published articles, of the 11 feigning measures administered, only the Test of Memory Malingering (TOMM; T. N. Tombaugh, 1996) retention trial had a specificity rate >.90 in the MR group. However, the 2nd learning trial of the TOMM, as well as a short form of the Digit Memory Test (T. J. Guilmette, K. J. Hart, A. J. Guiliano, & B. E. Leininger, 1994), approached this level of specificity, with both at .88. These results raise concerns about the specificity rates at recommended cutting scores of commonly used feigning tests in defendants with MR., (PsycINFO Database Record (c) 2010 APA, all rights reserved.)

Learning effects were assessed for the block design (BD) task, on the basis of variation in 2 stimulus parameters: perceptual cohesiveness (PC) and set size uncertainty (U). Thirty-one nonclinical undergraduate students (19 female) each completed 3 designs for each of 4 varied sets of the stimulus parameters (high-PC/high-U, high-PC/low-U, low-PC/high-U, and low-PC/low-U), ordered randomly within a larger set of designs with mixed stimulus characteristics. Regression analyses revealed significant, although modest, learning effects in all conditions. Negative-logarithmic learning slopes (growth factors) were greatest for high-U/high-PC designs and smallest for low-U/low-PC designs. Comparison of these slopes with known Wechsler Adult Intelligence Scale (3rd ed.; D. Wechsler, 1997; and 4th ed.; D. Wechsler, 2008) BD subtest gain scores demonstrated that presenting novel test items matched on stimulus parameters in multiple administrations reduced learning effects compared with the repeated use of the same test items. The results suggest that repeated administration of novel test items of the BD subtest, matched for PC and U, would result in more accurate assessments of changes in examinees' abilities over time than would the use of the same items. Difficulties inherent in implementing this method are also discussed.

The correlation between a short-form (SF) test and its full-scale (FS) counterpart is a mainstay in the evaluation of SF validity. However, in correcting for overlapping error variance in this measure, investigators have overattenuated the validity coefficient through an intuitive misapplication of P. Levy's (1967) formula. The authors of the present article clarify that such corrections should be based on subtest-level versus FS-level data. Additionally, the authors propose a simple, modified equation incorporating FS-level scores that provides liberal and conservative validity measures for comparison across estimation methods, and they demonstrate its use in both a normative (N = 2,450) and clinical psychiatric (N = 216) sample.

Profile Analysis via Multidimensional Scaling (PAMS) is a procedure for extracting latent core profiles in a multitest data set. The PAMS procedure offers several advantages compared with other profile analysis procedures. Most notably, PAMS estimates individual profile weights that reflect the degree to which an individual's observed profile approximates the shape and scatter of latent core profiles. The PAMS procedure was applied to index scores of nonreplicated participants from the standardization sample (N = 1,033) for the Wechsler Memory Scale--Third Edition (D. Tulsky, J. Zhu, & M. F. Ledbetter, 2002). PAMS extracted discrepant visual memory and auditory memory versus working memory core profiles for the complete 16- to 89-year-old sample and discrepant working memory and auditory memory versus working memory core profiles for the 75- to 89-year-old cohort. Implications for use of PAMS in future research are discussed.

An eight-subtest short form (SF8) of the Wechsler Adult Intelligence Scale, Third Edition (WAIS-III), maintaining equal representation of each index factor, was developed for use with psychiatric populations. Data were collected from a mixed inpatient/outpatient sample (99 men and 101 women) referred for neuropsychological assessment. Psychometric analyses revealed an optimal SF8 comprising Vocabulary, Similarities, Arithmetic, Digit Span, Picture Completion, Matrix Reasoning, Digit Symbol Coding, and Symbol Search, scored by linear scaling. Expanding on previous short forms, the current SF8 maximizes the breadth of information and reduces administration time while maintaining the original WAIS-III factor structure., ((c) 2007 APA, all rights reserved)

Examination of measurement invariance tests the assumption that the model underlying a set of test scores is directly comparable across groups. The observation of measurement invariance provides fundamental evidence for the inference that scores on a test afford equivalent measurement of the same psychological traits among diverse groups. Groups may be derived from different psychosocial backgrounds or different clinical presentations. In the Wechsler Adult Intelligence Scale-III (WAIS-III)/Wechsler Memory Scale-III (WMS-III) Technical Manual (Psychological Corporation, 2002), there appears to be a breakdown in factor structure among the standardization cases in older adults. In this study, the authors evaluated the invariance of the measurement model of the WAIS-III across 5 age bands. All components of the measurement model were examined. Overall, the evidence pointed to invariance across age of a modified 4-factor model that included cross-loadings for the Similarities and Arithmetic subtests. These results support the utility of the WAIS-III as a measure of stable intelligence traits across a wide age range.

A confirmatory factor analysis was conducted on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; D. Wechsler, 1991) with a sample of 579 Australian children referred for assessment because of academic difficulties in the classroom. The children were administered the WISC-III as part of the initial eligibility determination process for funding of special education services. The children were aged between 6 years and 16 years 7 months. One-, two-, three-, and four-factor models were tested. The four-factor model proposed in the WISC-III manual fit the data significantly better than all other models tested.

The Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; Wechsler, 1997b) provides factor-based index scores but allows only for pairwise comparison of these scores, producing inflated Type I error rates and reducing profile interpretability. This article provides tables for simultaneous comparison to the overall mean index score, thus reducing error rates and aiding interpretation. The Working Memory Index or Processing Speed Index can also be specifically compared when an individual is believed to have a condition, such as a learning disability or traumatic brain injury, associated with the selective depression of these indexes. Tables for the infrequency of specific differences are also provided, allowing the practitioner to note how unusual an obtained difference is in the general population.

In the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; D. Wechsler, 1997), the manual reports several confirmatory factor analyses in support of the instrument's latent factor structure. In practice, examiners frequently compare an examinee's score from a current administration of the WAIS-III with the results from a previous test administration. Implicit in test-retest score comparisons is evidence that scores retain similar interpretive meaning across time. Establishing an instrument's factorial invariance provides the foundation for this practice. This study investigated the factorial invariance of the WAIS-III across the instrument's 13 age groups. The overall results from this study generally support both configural and factorial invariance of the WAIS-III when the 11 primary tests are administered., (((c) 2004 APA, all rights reserved))

The reliability and validity of various short forms of the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; D. Wechsler, 1997) were evaluated in a sample of 100 patients with traumatic brain injury and in a demographically matched subgroup from the standardization sample. All short forms were based on 2-subtest estimations of the respective factor indexes. Although acceptable estimates could be obtained from all short forms for Verbal Comprehension, none of the possible short forms for Perceptual Organization consistently met the minimum criterion regarding the percentage of cases that fell within the 90% confidence interval of the full-length index. It is concluded that short-form estimates of the WAIS-III are not appropriate for clinical use when the goal is to obtain factor indexes.

The Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; D. Wechsler, 1997) permits the calculation of both traditional IQ and index scores. However, if only the subtests constituting the index scores are administered, especially those yielding the Verbal Comprehension and Perceptual Organization Indexes, there is no equivalent measure of Full Scale IQ. Following the procedure for calculating a General Ability Index (GAI; A. Prifitera, L. G. Weiss, & D. H. Saklofske, 1998) for the Wechsler Intelligence Scale for Children--Third Edition (D. Wechsler, 1991), GAI normative tables for the WAIS-III standardization sample are reported here.

The cumulative percentage frequencies are presented for differences among reliable component analysis (RCA) scores for the verbal comprehension, perceptual organization, freedom from distractibility, and processing speed constructs assessed by the Wechsler Intelligence Scale for Children--Third edition (WISC-III) for the standardization sample and a learning disabled sample. Using RCA scores to form differences has several advantages over traditional equally weighted scores for the WISC-III. J. C. Caruso and N. Cliff (2000) presented tables to assess the statistical significance of differences among the RCA scores for the WISC-III. It is important, however, to use a dual approach in interpreting difference scores; both the statistical significance of a difference and the frequency with which it occurred in a relevant comparison group should be determined. This article contains the information necessary for practitioners to use the recommended dual approach to interpreting RCA difference scores for the WISC-III.

Exploratory and confirmatory factor analyses of the subtests of the Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; D. Wechsler, 1997b) were conducted on a stratified sample of Canadian adults (n = 718). As was previously demonstrated for the children's version of this scale, the factor model of the American standardization sample was replicated across this Canadian national sample. Results of the factor analyses confirmed the presence of the 4 WAIS-III factors: Verbal Comprehension, Perceptual Organization, Working Memory, and Processing Speed.

Equations for prorating the Wechsler Memory Scale--III (WMS-III) Index scores were derived and validated on a sample of 252 mixed clinical cases. Regression equations were performed using age-scaled scores as predictors and the sum of age-scaled scores for Immediate Memory (IM) and General Memory (GM) as the criteria. Including Logical Memory and Verbal Paired Associates with either Faces or Family Pictures resulted in estimated scores that accounted for 95% to 97% of the variance for IM and GM. Over 80% of these cases had estimated sum of scaled scores that fell within 3 points of actual sum of scaled scores, within 1 standard error of measurement. When only Logical Memory and Verbal Paired Associates were included, estimations accounted for only 87% of the variance, and only 60% of the estimated scores fell within 3 points of actual sum of scaled scores. The regression equations are presented, as are the confidence intervals derived from a bootstrapping procedure that created 15,000 different samples.

The use of cognitive subtest profiles to hypothesize about children's learning strengths and weaknesses implicitly assumes that subtest profiles are predictive of academic performance. To test this assumption, Wechsler Intelligence Scale for Children-Third Edition (WISC-III) subtest profiles were decomposed into elevation, scatter, and shape components and sequentially regressed onto reading and math achievement scores for 1,118 nonexceptional and 538 exceptional students. Profile elevation was statistically and practically significant for both exceptional (R = .36-.61) and nonexceptional (R = .72-.75) students. Profile scatter did not aid in the prediction of achievement. Profile shape accounted for an additional 5%-8% of the variance in achievement measures. It was concluded that using WISC-III subtest scatter and shape to predict academic performance was not supported by the accumulated scientific evidence.

Wechsler Intelligence Scale for Children--Third Edition index score differences are generally interpreted cautiously, if at all, primarily because of their poor reliability. On the basis of prior analyses with the Wechsler Adult Intelligence Scale--Third Edition (J. C. Caruso & N. Cliff, 1999), it was hypothesized that differences between scores defined by reliable component analysis would have higher reliability than those defined by traditional equal weighting. Differences between the reliable component scores showed substantially higher reliability than equally weighted score differences. The differences between reliable component scores were also substantially more reliable than those derived from the weighted scores suggested by K. C. H. Parker and L. Atkinson (1994). Using the weights provided in this article will allow researchers and practitioners to compute the RCA scores and have the assurance of high reliability with its attractive consequences.

Clinical lore suggests that the Wechsler Intelligence Scale for Children--Third Edition (D. M. Wechsler, 1991) Comprehension and Picture Arrangement scores may be used as indices of social intelligence. This study evaluated this supposition by comparing these subtest scores with mother- and teacher-reported social functioning in 142 children with ADHD and 30 control children. After general intelligence was partialled out, the Comprehension subtest related to some aspects of social functioning, but the clinical significance of this was limited. The Picture Arrangement subtest was unrelated to social functioning, once general intelligence was controlled. These findings were consistent across study groups.