Validity of the Wechsler abbreviated scale of intelligence and other very short forms of estimating intellectual functioning

Performance on the Wechsler Adult Intelligence Scale-III (WAIS-III) was compared to performance on the Wechsler Abbreviated Scale of Intelligence (WASI), as well as short form estimations of intellectual functioning derived from WAIS-III performance, in a mixed clinical sample of 72 participants. The WASI verbal IQ (VIQ) score was significantly higher than the WAIS-III VIQ, whereas performance IQ (PIQ) estimates all differed from actual WAIS-III PIQ and full scale IQ (FSIQ). Correlations of WAIS-III scores with WASI scores were consistently lower than were correlations between the WASI-III and all other short forms. Although maintaining administration times of 15 minutesfor a two-subtest FSIQ and 30 minutes for a four-subtest FSIQ, the WASI did not consistently demonstrate desirable accuracy in predicting scores obtained from the WAIS-III. The results suggest that clinicians should use the WASI cautiously if at all, especially when accurate estimates of individuals' WAIS-III results are needed.     

Effects on WAIS-III performance IQ (PIQ) and full scale IQ (FSIQ) when object assembly is substituted for each standard performance scale subtest

According to the WAIS-III Administration and Scoring Manual, Object Assembly (OA) may be substituted for any spoiled Performance subtest. This assertion has not been evaluated in a clinical sample. The present investigation reports differences that resulted in Performance IQ (PIQ) and Full Scale IQ (FSIQ) when OA replaced each of the Performance subtests. Participants were 47 referrals for neuropsychological assessment (age M = 45.98 years, SD = 9.82; education M = 13.82 years, SD = 2.78). Results indicated that OA may replace any Performance subtest without seriously altering the summary scores. Differences between the standard IQs and OA-based composites were < 2 points for PIQ and < 1 point for FSIQ. More than 90% of the OA-based composites fell within the 90% confidence limits of the corresponding IQ.     

Estimation of Wechsler Adult Intelligence Scale-III index scores with the 7-subtest short form in a clinical sample

A 7-subtest short form of the Wechsler Adult Intelligence Scale-III (WAIS-III) previously demonstrated good comparability in estimating Full Scale and Verbal IQ summary scores, with adequate comparability in estimating Performance IQ. In a mixed clinical sample of 295 patients, the current study assessed the equivalence of the index scores generated from the full and prorated WAIS-III. The results revealed correlations corrected for redundancy of .90, .86, .87, and .75 for the Verbal Comprehension (VCI), Perceptual Organization (POI), Working Memory (WMI), and Processing Speed (PSI) indexes, respectively. Although the 7-subtest short form of the WAIS-III was not designed to estimate index scores, adequate estimates are viable for VCI, POI, and WMI when the goal is to obtain group, rather than individual, data points.     

Graduate student WAIS-III scoring accuracy is a function of full scale IQ and complexity of examiner tasks

Research on the Wechsler Adult Intelligence Scale-Revised and Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) suggests that practicing clinical psychologists and graduate students make item-level scoring errors that affect IQ, index, and subtest scores. Studies have been limited in that Full-Scale IQ (FSIQ) and examiner administration, recording, and scoring tasks have not been systematically varied. In this study, graduate student participants score a high (FSIQ = 112) and low (FSIQ = 85) IQ record form in one of two stimulus conditions: digitized film clips (N = 13) or partially completed record forms (N = 11). Results demonstrate that examiners are less accurate in the high IQ condition, and that recording examinee responses from scoring video clips results in more scoring errors. Obtained FSIQs are significantly higher than criterion IQ scores in the high IQ condition (8.46 for video condition, 2.55 for record form condition). Self-reported proficiency in WAIS-III administration and scoring is positively related to number of scoring errors.     

Seemingly anomalous full scale IQ scores on the WAIS-III and the WISC-III

The Canadian and American WISC-III and the American WAIS-III standardization data were used to investigate the prevalence of “seemingly anomalous” Full Scale IQ (FSIQ) scores for all possible Verbal and Performance sums of scale score combinations. It was found that 6% of FSIQ scores in these three samples were seemingly anomalous (i.e., fell outside of their associated VIQ/PIQ intervals). Interestingly, the anomalous FSIQ scores were more prevalent at the extremes of the FSIQ distribution, and did not occur when the VIQ/PIQ interval was greater than 12. Additionally, anomalous FSIQ scores were generally further from the center of the FSIQ distribution than were the associated VIQ and PIQ scores. Also, when the VIQ/PIQ interval contained FSIQ (the non-anomalous case), FSIQ tended to be located distally in the half-segment of the VIQ/PIQ interval furthest from the center of the FSIQ distribution. A statistical explanation for the findings is provided. Portions of this paper were presented March 3, 2000 at the 14th Annual Joseph R. Royce Research Conference, Department of Psychology, University of Alberta, Edmonton, Alberta. An erratum to this article is available at .     

Scoring reliability on the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III)

Nineteen psychologists and 19 graduate students scored two Wechsler Adult Intelligence Scale-Third Edition patient protocols. Mean IQs and indexes were similar across groups, but the ranges for Verbal IQ (VIQ), Performance IQ (PIQ), and Full Scale IQ (FSIQ) on one protocol were 25, 22, and 11 points, respectively. For both protocols taken together, percentages of agreement with the "actual" IQs for psychologists were only 26.3 for VIQ, 36.8 for PIQ, and 42.1 for FSIQ. For students, percentages were 15.8 for VIQ, 23.7 for PIQ, and 31.6 for FSIQ. The percentages of FSIQs that fell within +/- 1 standard error of measurement of the actual IQs were 89.5 for psychologists and 76.3 for students. Scoring error also had a negative impact on index scores. Both groups were confident about their scoring accuracy.     

Seemingly anomalous full scale IQ scores on the WAIS-III and the WISC-III

The Canadian and American WISC-III and the American WAIS-III standardization data were used to investigate the prevalence of “seemingly anomalous” Full Scale IQ (FSIQ) scores for all possible Verbal and Performance sums of scale score combinations. It was found that 6% of FSIQ scores in these three samples were seemingly anomalous (i.e., fell outside of their associated VIQ/PIQ intervals). Interestingly, the anomalous FSIQ scores were more prevalent at the extremes of the FSIQ distribution, and did not occur when the VIQ/PIQ interval was greater than 12. Additionally, anomalous FSIQ scores were generally further from the center of the FSIQ distribution than were the associated VIQ and PIQ scores. Also, when the VIQ/PIQ interval contained FSIQ (the non-anomalous case), FSIQ tended to be located distally in the half-segment of the VIQ/PIQ interval furthest from the center of the FSIQ distribution. A statistical explanation for the findings is provided. Portions of this paper were presented March 3, 2000 at the 14th Annual Joseph R. Royce Research Conference, Department of Psychology, University of Alberta, Edmonton, Alberta. An erratum to this article is available at .     

Two-subtest estimations of WAIS-III factor index scores

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 validity of the general ability measure for adults: comparison with WAIS-R IQ scores in a sample of college students with academic difficulties

The present study investigated the validity of the General Ability Measure for Adults (GAMA) by comparing it to the WAIS-R using a sample of 80 college students reporting learning difficulties. Results indicated that the mean GAMA IQ score did not deviate significantly from the mean WAIS-R IQ scores. The GAMA Full Scale IQ correlated significantly with the WAIS-R PIQ, VIQ, and FSIQ scores. However, the obtained correlation coefficient for the GAMA and WAIS-R PIQ significantly differed from the observed correlation coefficient between the GAMA and WAIS-R VIQ, suggesting that the GAMA was more clearly associated with perceptual skills than verbal abilities. When the correlation coefficients between the GAMA and WAIS-R scores were corrected for the effects of range restriction, the correlation coefficients increased, yet demonstrated the same pattern (e.g., GAMA/PIQ,.69; GAMA/VIQ,.36; GAMA/FSIQ,.60). The GAMA s accuracy in predicting individual student performance on the WAIS-R FSIQ also was examined.     

Comparison of Tetradic WAIS-III Short Forms in Predicting Full Scale IQ Scores in Neuropsychiatric Clinic Settings

Patients from two neuropsychology clinics (n = 283) were divided into model development (n = 189) and validation samples (n = 94) with proportional representation from each clinic. Three regression based models of four WAIS-III subtests were developed and cross-validated to evaluate their FSIQ estimation accuracy: (1) an optimized stepwise regression model derived from the development sample (Comprehension, Matrix Reasoning, Similarities, and Picture Arrangement), (2) an a priori WASI based model (Similarities, Matrix Reasoning, Vocabulary, and Block Design), and (3) an a priori model with relatively rapidly administered subtests from each Index Score factor of the WAIS-III (Information, Picture Completion, Arithmetic, and Digit Symbol-Coding). The models produced good (92 to 97%) FSIQ estimation accuracy within 10 points of FSIQ with none of these models performing significantly better than another. The utility of clinical use of short form FSIQ estimation is a function of accuracy needed versus administration time reduction and ease for the patient.     

Development of an eight-subtest short form of the WISC-IV and evaluation of its clinical utility in children with traumatic brain injury

This study evaluated the degree to which an 8-subtest short form of the Wechsler Intelligence Scale for Children—Fourth Edition would yield acceptable estimates of the long-form Full-Scale IQ index while clarifying the underlying factor structure in a sample of 100 children and adolescents with traumatic brain injury. The short-form Full-Scale IQ had sufficient (i.e., at least two thirds) nonerror covariance with its full-length counterpart. In addition, a sufficient proportion (i.e., > 80%) of these short-form estimates fell within the 90% confidence interval of the respective full-length scores. Importantly, the elimination of 2 subtests, and in particular the Picture Concepts subtest, resulted in a factor structure where each remaining subtest was fairly specifically associated with its intended scale. It is concluded that this short form can be used clinically in children with traumatic brain injury without sacrificing reliability and with more straightforward interpretability at the level of the factor index scores.     

Use of population-specific parameters in generating WAIS-R short forms

One method of increasing the validity of WAIS-R short forms in estimating the standard WAIS-R Full Scale IQ is by using population-specific parameters in generating WAIS-R short forms. Three studies were conducted to evaluate (1) the contribution of age-scaled scores in generating accurate short-form Full Scale IQ, (2) the psychometric properties (validity and reliability) of WAIS-R subtests with a heterogeneous psychiatric population and subsequent development of short forms based on these properties, and (3) the validity of these short forms with respect to Silverstein's (1982) and Cyr and Brooker's (1984) 2- and 4-subtest combinations. Analyses showed (1) the use of age-scaled scores did not increase validity, (2) different subtest combinations were generated based on the population-specific parameters, and (3) increases in validity occurred for some short forms derived from the clinical sample. Despite increases in validity, clinicians and researchers are cautioned about the use of short forms in clinical practice.     

Identification of mental retardation by the system of multicultural pluralistic assessment: Nondiscriminatory or nonexistent?

The effects of applying the dual-criterion classification system for mental retardation in connection with the System of Multicultural Pluralistic Assessment (SOMPA) were investigated by using the SOMPA standardization sample as subjects. Average scaled scores on the Adaptive Behavior Inventory for Children (ABIC) were paired (a) with Full Scale IQ (FSIQ) Wechsler Intelligence Scale for Children-Revised or (b) with the SOMPA-derived Estimated Learning Potential (ELP). The children performing below the third percentile on either combination of measures were thus classified as “mentally retarded.” By the FSIQ and ELP procedures, 0.6% and 0.2%, respectively, of the children were so classified; the overwhelming majority of the children were of minority background. The implications for the diagnostic category of mild mental retardation and the further use of the SOMPA are discussed.     

Expanding the ecological validity of WAIS-IV and WMS-IV with the Texas functional living scale

Assessment of functional status is an important aspect of clinical evaluation. As part of the standardization of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) and Wechsler Memory Scale-Fourth Edition (WMS-IV), participants completed the Texas Functional Living Scale (TFLS), a measure of Instrumental Activities of Daily Living. The relationships between TFLS and WAIS-IV and WMS-IV were examined in both normally developing and clinical samples. In general, the highest correlations were between TFLS and measures of general cognitive ability (WAIS-IV FSIQ [Full Scale IQ] and GAI [General Ability Index]) and working memory (WAIS-IV WMI [Working Memory Index] and WMS-IV VWMI [Visual Working Memory Index]). Across the clinical populations, working memory subtests were generally strongly related to TFLS performance, although this relationship was more consistent with WAIS-IV than WMS-IV. Contrast scaled scores are presented for the TFLS based on WAIS-IV or WMS-IV performance. These scores allow the evaluation of functional abilities within the context of cognitive and memory ability, enhancing and expanding the utility of the WAIS-IV and WMS-IV.     

Seemingly Anomalous WISC-IV Full Scale IQ Scores in the American and Canadian Standardization Samples

The American and Canadian standardization samples for the fourth edition of the Wechsler Intelligence Scale for Children were used to ascertain the prevalence of “seemingly anomalous” Full Scale IQ (FSIQ) scores for all possible sums of scaled scores combinations of the Verbal Comprehension Index, Perceptual Reasoning Index, Working Memory Index, and Processing Speed Index. About 1% of FSIQ scores in both samples were anomalous (that is, fell outside the range of the four indices). Interestingly, the prevalence of anomalous scores was higher at the extremes of the FSIQ distribution. Moreover, anomalous FSIQ scores occurring above or below the mean of the FSIQ distribution (that is, 100) were larger or smaller, respectively, than any of the four indices. Furthermore, if the range of the four indices did contain the FSIQ (the non-anomalous case), when the FSIQ was below or above 100 it tended to be located distally in the half-segment of the range furthest below or above 100, respectively. A non-technical intuitive analogy from Olympic sports and a statistical explanation for the findings are provided. Important implications for practitioners are also presented. Portions of this paper were presented March 17, 2006 at the 20th annual Joseph R. Royce Research Conference, Department of Psychology, University of Alberta, Edmonton, Alberta.     

Seemingly Anomalous WISC-IV Full Scale IQ Scores in the American and Canadian Standardization Samples

The American and Canadian standardization samples for the fourth edition of the Wechsler Intelligence Scale for Children were used to ascertain the prevalence of “seemingly anomalous” Full Scale IQ (FSIQ) scores for all possible sums of scaled scores combinations of the Verbal Comprehension Index, Perceptual Reasoning Index, Working Memory Index, and Processing Speed Index. About 1% of FSIQ scores in both samples were anomalous (that is, fell outside the range of the four indices). Interestingly, the prevalence of anomalous scores was higher at the extremes of the FSIQ distribution. Moreover, anomalous FSIQ scores occurring above or below the mean of the FSIQ distribution (that is, 100) were larger or smaller, respectively, than any of the four indices. Furthermore, if the range of the four indices did contain the FSIQ (the non-anomalous case), when the FSIQ was below or above 100 it tended to be located distally in the half-segment of the range furthest below or above 100, respectively. A non-technical intuitive analogy from Olympic sports and a statistical explanation for the findings are provided. Important implications for practitioners are also presented. Portions of this paper were presented March 17, 2006 at the 20th annual Joseph R. Royce Research Conference, Department of Psychology, University of Alberta, Edmonton, Alberta.     

Factor structure of the Wechsler Adult Intelligence Scale-III in schizophrenia

This report examines and compares the factor structure of the new edition of the Wechsler Adult Intelligence Scale (WAIS-III) in a sample of chronic schizophrenia and schizoaffective disorder outpatients (n = 120) and an age-matched sample of individuals drawn from the WAIS-III standardization sample (n = 200). Exploratory and confirmatory factor analyses similar to those reported by the developers of the scale suggested that a model of WAIS-III performance with correlated factors for verbal comprehension, perceptual organization, working memory, and processing speed fit the data from the schizophrenia sample as well as it fit the nonclinical comparison sample and fit the data from both samples better than alternative models.     

Meta-Analysis of Intelligence Quotient (IQ) in Obsessive-Compulsive Disorder

Obsessive compulsive disorder (OCD) is associated with a moderate degree of underperformance on cognitive tests, including deficient processing speed. However, despite little research focusing on Intelligence Quotient (IQ) in OCD, it has long been speculated that the disorder is associated with elevated intellectual capacity. The present meta-analytic study was, therefore, conducted to quantitatively summarize the literature on IQ in OCD systematically. We identified 98 studies containing IQ data among individuals with OCD and non-psychiatric comparison groups, and computed 108 effect sizes for Verbal IQ (VIQ, n = 55), Performance IQ (PIQ, n = 13), and Full Scale IQ (FSIQ, n = 40). Across studies, small effect sizes were found for FSIQ and VIQ, and a moderate effect size for PIQ, exemplifying reduced IQ in OCD. However, mean IQ scores across OCD samples were in the normative range. Moderator analyses revealed no significant moderating effect across clinical and demographic indices. We conclude that, although lower than controls, OCD is associated with normative FSIQ and VIQ, and relatively lowered PIQ. These results are discussed in light of neuropsychological research in OCD, and particularly the putative impact of reduced processing speed in this population. Recommendations for utilization of IQ tests in OCD, and directions for future studies are offered.     

The joint WAIS-III and WMS-III factor structure: development and cross-validation of a six-factor model of cognitive functioning

During the standardization of the Wechsler Adult Intelligence Scale (3rd ed.; WAIS-III) and the Wechsler Memory Scale (3rd ed.; WMS-III) the participants in the normative study completed both scales. This "co-norming" methodology set the stage for full integration of the 2 tests and the development of an expanded structure of cognitive functioning. Until now, however, the WAIS-III and WMS-III had not been examined together in a factor analytic study. This article presents a series of confirmatory factor analyses to determine the joint WAIS-III and WMS-III factor structure. Using a structural equation modeling approach, a 6-factor model that included verbal, perceptual, processing speed, working memory, auditory memory, and visual memory constructs provided the best model fit to the data. Allowing select subtests to load simultaneously on 2 factors improved model fit and indicated that some subtests are multifaceted. The results were then replicated in a large cross-validation sample (N = 858).     

Prereading skills of very-low-birth-weight prematurely born Finnish children

Our objective was to study the prereading skills of very-low-birth-weight (VLBW; ≤ 1500 g) prematurely born children at the age of five years. A regional cohort of 89 VLBW children and 152 full-term (FT) born children was assessed for letter knowledge, phonological processing, and speeded naming. Full-scale IQ (FSIQ) was assessed using a short version of WPPSI-R. The associations of parental and neonatal factors, and FSIQ with prereading skills were assessed. VLBW group had poorer prereading skills, and there were more VLBW children at-risk (performing < ?1 SD) compared to FT children in phonological processing (23% vs. 9%, p = .002), letter knowledge (27% vs. 14%, p = .017), and the accuracy of speeded naming (26% vs. 13%, p = .020). VLBW children had lower average FSIQ and Performance IQ (both comparisons p < .001) than FT controls, but Verbal IQ did not differ. When FSIQ was used as a covariate, VLBW children did not differ from the FT group in prereading skills indicating that they are at risk for more global developmental problems. Lower parental level of education as well as parent's reading problems were negatively associated with VLBW children's prereading skills. Positively, about 75% of VLBW children performed within the normal range in each individual prereading skill.