Psychological correlates of fatigue: Examining depression, perfectionism, and automatic negative thoughts

This study investigated whether depression, perfectionism or automatic negative thoughts would correlate with the symptomatology of fatigue in a non-clinical population. A structural model was developed to determine if depression or latent constructs of perfectionism and automatic negative thoughts would correlate with four components of fatigue (emotional distress, somatic symptomatology, general fatigue and cognitive difficulties). It was found that all aspects of fatigue were significantly correlated with depression and automatic negative thoughts, whereas only emotional distress and cognitive difficulties were correlated with perfectionism.Social Sciences and Humanities Research Counci

The effects of heteroscedasticity on tests of equivalence

Tests of equivalence, which are designed to assess the similarity of group means, are becoming more popular, yet very little is known about the statistical properties of these tests. Monte Carlo methods are used to compare the test of equivalence proposed by Schuirmann with modified tests of equivalence that incorporate a heteroscedastic error term. It was found that the latter were more accurate than the Schuirmann test in detecting equivalence when sample sizes and variances were unequal.Social Sciences and Humanities Research Counci

Group Level Clinical Significance: An Analysis of Current Practice

Measures of clinical significance offer important information about psychological interventions that cannot be garnered from tests of the statistical significance of the change from pretest to posttest. For example, post-intervention comparisons to a nonclinical group often offer valuable information about the practical value of the change that occurred. This study explored the manner in which researchers conduct clinical significance analyses in an effort to summarize the effectiveness of an intervention at the group level. The focus was on the use of the original Jacobson and Truax (Journal of Consulting and Clinical Psychology, 59, 12–19, 1991) method and the normative comparisons method due to Kendall et al. (Journal of Consulting and Clinical Psychology, 67, 285–299, 1999). The results highlight that although the Jacobson and Truax method is routinely adopted for summarizing group-level clinical significance, advanced strategies for summarizing the results are very infrequently applied. Further, the Kendall et al. method, which provides valuable and distinct information regarding how the treated group is performing relative to a normal comparison group, is rarely adopted and even when it is it is often not conducted appropriately. Recommendations are provided for conducting group-level clinical significance analyses.Social Sciences and Humanities Research Counci

Recommendations for applying tests of equivalence

Researchers in psychology reliably select traditional null hypothesis significance tests (e.g., Student's t test), regardless of whether the research hypothesis relates to whether the group means are equivalent or whether the group means are different. Tests of equivalence, which have been popular in biopharmaceutical studies for years, have recently been introduced and recommended to researchers in psychology for demonstrating the equivalence of two group means. However, very few recommendations exist for applying tests of equivalence. A Monte Carlo study was used to compare the test of equivalence proposed by Schuirmann with the traditional Student t test for deciding if two group means are equivalent. It was found that Schuirmann's test of equivalence is more effective than Student's t test at detecting population mean equivalence with large sample sizes; however, Schuirmann's test of equivalence performs poorly relative to Student's t test with small sample sizes and/or inflated variances.Social Sciences and Humanities Research Counci

Psychological Well-Being in Obese Inpatients with Ischemic Heart Disease at Entry and at Discharge from a Four-Week Cardiac Rehabilitation Program

The purposes of this observational pre-post study were twofold: 1- to evaluate psychological health in obese patients with ischemic heart disease at admission to cardiac rehabilitation (CR) and 2 – to examine the effectiveness of a 4-week CR residential program in improving obese patients’ psychological well-being at discharge from CR. A sample of 177 obese patients completed the Psychological General Well-Being Inventory (PGWBI) at admission to the CR program and at discharge. The equivalence testing method with normative comparisons was used to determine the clinical significance of improvements after having established that baseline mean scores on the PGWBI scales were significantly lower than normal means. Results show that patients scored equally or better than norms on many PGWBI dimensions at admission to CR but scored significantly worse on Global Score, Vitality and Self-control. At discharge, mean scores that were impaired at baseline returned to normal levels at the more conservative equivalence interval. A 4-week CR program was thus effective in improving obese patients’ psychological well-being. The equivalence testing method allowed to establish the clinical significance of such improvement