A. Alexander Beaujean

Bifactor Structure of the Wechsler Preschool and Primary Scale of Intelligence—Fourth Edition

The Wechsler Preschool and Primary Scale of Intelligence--Fourth Edition (WPPSI-IV; Wechsler, 2012) represents a substantial departure from its predecessor, including omission of 4 subtests, addition of 5 new subtests, and modification of the contents of the 5 retained subtests. Wechsler (2012) explicitly assumed a higher-order structure with general intelligence (g) as the second-order factor that explained all the covariation of several first-order factors but failed to consider a bifactor model. The WPPSI-IV normative sample contains 1,700 children aged 2 years and 6 months through 7 years and 7 months, bifurcated into 2 age groups: 2:6-3:11 year olds (n = 600) and 4:0-7:7 year olds (n = 1,100). This study applied confirmatory factor analysis to the WPPSI-IV normative sample data to test the fit of a bifactor model and to determine the reliability of the resulting factors. The bifactor model fit the WPPSI-IV normative sample data as well as or better than the higher-order models favored by Wechsler (2012). In the bifactor model, the general factor accounted for more variance in every subtest than did its corresponding domain-specific factor and the general factor accounted for more total and common variance than all domain-specific factors combined. Further, the domain-specific factors exhibited poor reliability independent of g (i.e., ωh coefficients of .05 to .33). These results suggest that only the general intelligence dimension was sufficiently robust and precise for clinical use.

The Effects of Wechsler Intelligence Scale for Children-Fourth Edition Cognitive Abilities on Math Achievement.

This study used structural equation modeling to examine the effect of Stratum III (i.e., general intelligence) and Stratum II (i.e., Comprehension-Knowledge, Fluid Reasoning, Short-Term Memory, Processing Speed, and Visual Processing) factors of the Cattell-Horn-Carroll (CHC) cognitive abilities, as operationalized by the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV; Wechsler, 2003a) subtests, on Quantitative Knowledge, as operationalized by the Wechsler Individual Achievement Test, Second Edition (WIAT-II; Wechsler, 2002) subtests. Participants came from the WISC-IV/WIAT-II linking sample (n=550). We compared models that predicted Quantitative Knowledge using only Stratum III factors, only Stratum II factors, and both Stratum III and Stratum II factors. Results indicated that the model with only the Stratum III factor predicting Quantitative Knowledge best fit the data.

The use of an anti-inflammatory supplement in patients with chronic kidney disease.

Abstract Chronic kidney disease (CKD) is characterized by a continuous reduction in kidney function, increased inflammation, and reduced antioxidant capacity. The objective of this study was to assess the effects of a herbal supplement on systemic inflammation and antioxidant status in non-dialysis CKD patients. Sixteen patients with CKD (56.0±16.0 yrs, 171.4±11.9 cm, 99.3±20.2 kg) were randomly chosen to receive a herbal supplement composed of Curcuma longa and Boswellia serrata, or placebo. Plasma levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), glutathione peroxidase (GPx), and serum C-reactive protein (CRP) were measured at baseline and 8 weeks. Baseline data demonstrated elevated inflammation and low antioxidant levels. A significant time effect (p=0.03) and time x compliance interaction effect (p=0.04) were observed for IL-6. No significant differences were observed for any other variables. This study demonstrates that mild and moderate CKD is associated with chronic inflammation and low antioxidant activity. Systemic inflammation and impaired antioxidant status may be greater in CKD populations with multiple comorbidities. Curcumin and Boswellia serrata are safe and tolerable and helped to improve the levels of an inflammatory cytokine.

The Structure of Cognitive Abilities in Youths with Manic Symptoms: A Factorial Invariance Study.

This study compared the structure of cognitive ability (specifically, verbal/crystallized [Gc] and visual-spatial ability [Gv]), as measured in the Wechsler Intelligence Scale for Children, in youth with manic symptoms with a nationally representative group of similarly aged youth. Multigroup confirmatory factor analysis found the majority of the estimated parameters were invariant between the groups, although there was a difference in the intercepts for the Similarities subtest and difference in unique variances for the Picture Completion, Comprehension, and Picture Arrangement subtests. Thus, although there are many neurological changes associated with manic symptoms, the structure of verbal/crystallized and visual-spatial abilities appear relatively robust and invariant. As Gc and Gv are the primary domains on all the Wechsler Intelligence Scales for Children, results also indicate that clinical interpretation of the Wechsler scales may be appropriate to measure cognitive performance in youths with manic symptoms.

An Item-Level Examination of the Factorial Validity of NEO Five-Factor Inventory Scores

The NEO Five-Factor Inventory (NEO-FFI) is often used in field-based research and clinical studies as it is designed to measure the same personality dimensions as the longer NEO Personality Inventory in a shorter time frame. In this study, the authors examined the reliability and structural validity of the NEO-FFI scores at the item level in a large sample of Jamaican young adults (N = 1,021; ages 17-24 years). Across different factor estimation and rotation methods, many NEO-FFI items performed poorly. Likewise, the estimated reliability of the NEO-FFI scores was poor (except Conscientiousness) across different estimations of reliability. These items and scores were then compared with other studies of the NEO-FFI that reported item-level pattern/structure coefficients or reliability estimates. Similarities in item performance and low reliability estimates across studies suggest that the items, rather than cultural differences, account for much of the poor performance of the NEO-FFI scores, especially in the domains of Extraversion, Openness to Experience, and Agreeableness.

Reverse Epidemiology of Lipid-Death Associations in a Cohort of End-Stage Renal Disease Patients

Background and Aims: Cardiovascular disease is the leading cause of death among end-stage renal disease (ESRD) patients with hypercholesterolemia as a major cause. A few studies have demonstrated counter-intuitive findings known as reverse epidemiology where normal levels of cholesterol are associated with higher levels of mortality. The purpose of this study was to determine if there are reverse epidemiological associations between lipid risk factors and mortality in ESRD patients. Methods: ESRD (n = 438) patients were recruited from 4 outpatient dialysis units. Patients were tracked for 36 months until study completion or death with mortality status as the outcome measure. Results: Analysis of covariance revealed significant differences at posttest and reverse epidemiological effects for total cholesterol (p = 0.0001), low-density lipoprotein cholesterol (LDL) (p = 0.023), LDL particle number (p = 0.0001), LDL size (p = 0.009), triglycerides (p = 0.0001), and very low-density lipoprotein cholesterol (p = 0.036). A step-wise linear regression revealed weak, but significant predictors of mortality with total cholesterol (β = 0.263, p = 0.017) and LDL (β = –0.177, p = 0.045). A Cox death hazard ratio revealed LDL size as a significant predictor of mortality in this study. Conclusions: Our study discovered reverse epidemiology in a number of lipid variables. Additionally regression revealed that LDL and total cholesterol were predictors of mortality with lower levels being more predictive of death.

Reproducing the Wechsler Intelligence Scale for Children–Fifth Edition Factor Model Results

One of the ways to increase the reproducibility of research is for authors to provide a sufficient description of the data analytic procedures so that others can replicate the results. The publishers of the Wechsler Intelligence Scale for Children–Fifth Edition (WISC-V) do not follow these guidelines when reporting their confirmatory factor analysis results. Consequently, scholars have been frustrated when they have tried to replicate the results in the WISC-V technical manual. I explain how the WISC-V publishers set the scale of their latent variables and demonstrate how to replicate the WISC-V models using the R statistical program.

A Multitrait—Multimethod Examination of the Reynolds Intellectual Assessment Scales in a College Sample

This study assessed trait validity of the Reynolds Intellectual Assessment Scales’ (RIAS) Verbal Index (VIX) and Nonverbal Index (NIX) scores in a group of college students. Using both observation of patterns and latent variable modeling of a multitrait—multimethod correlation/covariance matrix, the results indicate that the RIAS VIX scores behaved in a manner predicted from the theory behind their construction; namely, they related strongly to other measures of crystallized intelligence (Gc) and, together, they formed a salient Gc factor. The NIX scores, however, did not behave as predicted—showing as strong, or stronger, associations with measures of Gc than measures of fluid intelligence. Although more studies of this type are needed across different samples before making broad generalizations, the results from the present study support the use and interpretation of the RIAS VIX score, but not the NIX score.

Using the social cognitive theory to understand physical activity among dialysis patients

PURPOSE/OBJECTIVE The purpose of this study was to use the social cognitive theory (SCT) constructs self-efficacy, outcome expectations, and self-regulation to better understand associations of physical activity (PA) behaviors among dialysis patients after controlling for demographic and health-related factors. RESEARCH METHOD/DESIGN This study was cross-sectional in design. Participants (N = 115; mean age = 61.51 years, SD = 14.01) completed self-report questionnaires during a regularly scheduled dialysis treatment session. Bivariate and hierarchical linear regression analyses were conducted to examine relationships among SCT constructs and PA. RESULTS Significant relationships between PA and self-efficacy (r = .336), self-regulation (r = .280), and outcome expectations (r = .265) were detected among people on dialysis in bivariate analyses. Hierarchical linear regression revealed significant increases in variance explained for the addition of self-efficacy, self-regulation, and covariates (p < .01). Younger age, self-efficacy, and self-regulation were associated (p < .10) with greater participation in physical activity in the final model (R² = .272). Conclusion/Implication: This research supports the use of SCT in understanding PA among people undergoing dialysis treatment. The findings of this study can help health educators and health care practitioners better understand PA and how to promote it among this population. Future research should further investigate which activities dialysis patients participate in across the life span of their disease. Future PA programs should focus on increasing a patients self-efficacy and self-regulation.

An Analysis of Cross Racial Identity Scale Scores Using Classical Test Theory and Rasch Item Response Models

Item response models (IRMs) were used to analyze Cross Racial Identity Scale (CRIS) scores. Rasch analysis scores were compared with classical test theory (CTT) scores. The partial credit model demonstrated a high goodness of fit and correlations between Rasch and CTT scores ranged from .91 to .99. CRIS scores are supported by both methods.