Blair T. Johnson

Gender and leadership style: A meta-analysis

Research comparing the leadership styles of women and men is reviewed, and evidence is found for both the presence and the absence of differences between the sexes. In contrast to the gender-stereotypic expectation that women lead in an interpersonaily oriented style and men in a task-oriented style, female and male leaders did not differ in these two styles in organizational studies. However, these aspects of leadership style were somewhat gender stereotypic in the two other classes of leadership studies investigated, namely (a) laboratory experiments and (b) assessment studies, which were denned as research that assessed the leadership styles of people not selected for occupancy of leadership roles. Consistent with stereotypic expectations about a different aspect of leadership style, the tendency to lead democratically or autocratically, women tended to adopt a more democratic or participative style and a less autocratic or directive style than did men. This sex difference appeared in all three classes of leadership studies, including those conducted in organizations. These and other findings are interpreted in terms of a social role theory of sex differences in social behavior.

Initial Severity and Antidepressant Benefits: A Meta-Analysis of Data Submitted to the Food and Drug Administration

Background Meta-analyses of antidepressant medications have reported only modest benefits over placebo treatment, and when unpublished trial data are included, the benefit falls below accepted criteria for clinical significance. Yet, the efficacy of the antidepressants may also depend on the severity of initial depression scores. The purpose of this analysis is to establish the relation of baseline severity and antidepressant efficacy using a relevant dataset of published and unpublished clinical trials. Methods and Findings We obtained data on all clinical trials submitted to the US Food and Drug Administration (FDA) for the licensing of the four new-generation antidepressants for which full datasets were available. We then used meta-analytic techniques to assess linear and quadratic effects of initial severity on improvement scores for drug and placebo groups and on drug–placebo difference scores. Drug–placebo differences increased as a function of initial severity, rising from virtually no difference at moderate levels of initial depression to a relatively small difference for patients with very severe depression, reaching conventional criteria for clinical significance only for patients at the upper end of the very severely depressed category. Meta-regression analyses indicated that the relation of baseline severity and improvement was curvilinear in drug groups and showed a strong, negative linear component in placebo groups. Conclusions Drug–placebo differences in antidepressant efficacy increase as a function of baseline severity, but are relatively small even for severely depressed patients. The relationship between initial severity and antidepressant efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication.

The self-reference effect in memory: A meta-analysis.

In this review, the authors examine the basis for the mnemonic superiority that results from relating material to the self. A meta-analysis confirms the expected self-reference effect (SRE) in memory, with self-referent encoding strategies yielding superior memory relative to both semantic and other-referent encoding strategies. Consistent with theory and research that suggest self-reference (SR) produces both organized and elaborate processing, the SRE was smaller (a) when SR is compared with other-reference (OR) rather than semantic encoding and (b) when the comparison tasks promote both organization and elaboration. Thus, the SRE appears to result primarily because the self is a well-developed and often-used construct that promotes elaboration and organization of encoded information. The authors discuss the implications of these and other findings for theories of the SRE and for future research.

Computer-delivered interventions for health promotion and behavioral risk reduction: a meta-analysis of 75 randomized controlled trials, 1988-2007.

OBJECTIVE The use of computers to promote healthy behavior is increasing. To evaluate the efficacy of these computer-delivered interventions, we conducted a meta-analysis of the published literature. METHOD Studies examining health domains related to the leading health indicators outlined in Healthy People 2010 were selected. Data from 75 randomized controlled trials, published between 1988 and 2007, with 35,685 participants and 82 separate interventions were included. All studies were coded independently by two raters for study and participant characteristics, design and methodology, and intervention content. We calculated weighted mean effect sizes for theoretically-meaningful psychosocial and behavioral outcomes; moderator analyses determined the relation between study characteristics and the magnitude of effect sizes for heterogeneous outcomes. RESULTS Compared with controls, participants who received a computer-delivered intervention improved several hypothesized antecedents of health behavior (knowledge, attitudes, intentions); intervention recipients also improved health behaviors (nutrition, tobacco use, substance use, safer sexual behavior, binge/purge behaviors) and general health maintenance. Several sample, study and intervention characteristics moderated the psychosocial and behavioral outcomes. CONCLUSION Computer-delivered interventions can lead to improved behavioral health outcomes at first post-intervention assessment. Interventions evaluating outcomes at extended assessment periods are needed to evaluate the longer-term efficacy of computer-delivered interventions.

Attitudes toward older and younger adults: A meta-analysis.

Attitudes toward the elderly have been examined in a number of empirical studies, yet the question of whether the elderly are viewed more negatively than younger persons has not been resolved. A meta-analysis of the literature was conducted to examine this question; results demonstrated that attitudes toward the elderly are more negative than attitudes toward younger people. However, smaller differences between the evaluations of elderly and younger targets were found when (a) the study used measures of personality traits (compared with measures of competence), (b) there were a larger number of dependent measures included in the effect size, (c) specific information was provided about the target person (compared with when a general target such as old person was used), and (d) a between-subjects design (compared with a within-subjects design) was used. These results support Lutskys (1981) conclusion that age, in and of itself, seems to be less important in determining attitudes toward the elderly than other types of information. The methodological limitations within the literature and a need to consider multiple components of attitudes toward older individuals are discussed.

Elevated blood pressure and personality: a meta-analytic review

A meta-analysis of 295 relevant effect sizes obtained from 25,469 participants confirmed expectations that elevated blood pressure (BP) and essential hypertension (EH) would be associated with lower affect expression but with more negative affectivity and defensiveness. The strongest associations occurred for defensiveness and measures of anger and affect expression linked to an interpersonal context(s). However, a number of other factors also were found to moderate associations of BP with personality measures, including awareness of BP status, gender, occupation, and diastolic versus systolic BP assessment. Given these moderators, the authors conclude that a traditional view of personality causing EH is untenable and that, not incorporating multifactorial, synergistic approaches is likely to obscure associations of personality-behavior with EH.

Efficacy of Exercise Interventions in Modulating Cancer-Related Fatigue among Adult Cancer Survivors: A Meta-Analysis

Background: The purpose of this meta-analysis was to explore the efficacy of exercise as a nonpharmacologic intervention to reduce cancer-related fatigue (CRF) among adult cancer survivors. We also investigated how different components of the exercise prescription (Ex Rx), methodologic considerations, and subject characteristics modulate CRF. Methods: A systematic search for randomized controlled trials was conducted using words related to cancer, exercise, and fatigue. Results: In total, 44 studies with 48 interventions qualified, including 3,254 participants of varying cancer types, stages of diagnosis, treatments, and exercise interventions. Cancer survivors in exercise interventions reduced their CRF levels to a greater extent than usual care controls, d+ = 0.31 (95% CI = 0.22–0.40), an effect that appeared to generalize across several types of cancer. CRF levels improved in direct proportion to the intensity of resistance exercise (β = 0.60, P = 0.01), a pattern that was stronger in higher quality studies (β = 0.23, P < 0.05). CRF levels also reduced to a greater extent when interventions were theoretically driven (β = 0.48, P < 0.001) or cancer survivors were older (β = 0.24, P = 0.04). Conclusions: Exercise reduced CRF especially in programs that involved moderate-intensity, resistance exercise among older cancer survivors and that were guided by theory. Impact: Our results indicate exercise interventions for adult cancer survivors should be multi-dimensional and individualized according to health outcome and cancer type. Cancer Epidemiol Biomarkers Prev; 20(1); 123–33. ©2011 AACR.

Are black-white differences in females' body dissatisfaction decreasing? A meta-analytic review.

Proponents of the sociocultural model of eating disorders have suggested that ethnic differences in body dissatisfaction may be diminishing as the thin ideal of beauty becomes more widely disseminated among minority women. In a meta-analysis, the authors examined temporal trends in Black-White differences and also examined whether these differences generalize across various age groups and measures. Results confirmed more favorable body image evaluations among Black than White females, with the greatest differences at the age period of the early 20s. Although results confirmed that ethnic differences have diminished, this trend was limited to weight-focused measures. On more global body image measures, ethnic differences actually increased. These results suggest that the relationship between Black-White ethnicity and body image is more complex than previously suggested.

Exercise Interventions for Cancer Survivors: A Meta-Analysis of Quality of Life Outcomes

BackgroundExercise improves quality of life (QOL) in cancer survivors, although characteristics of efficacious exercise interventions for this population have not been identified.PurposeThe present meta-analysis examines the efficacy of exercise interventions in improving QOL in cancer survivors, as well as features that may moderate such effects.MethodStudies were identified and coded, and QOL effect sizes were calculated and analyzed for trends.ResultsOverall, exercise interventions increased QOL, but this tendency depended to some extent on exercise and patient features. Although several features were associated with effect sizes, models revealed that interventions were particularly successful if they targeted more intense aerobic exercise and addressed women. These tendencies emerged over longer periods of time and were more prominent in studies with higher methodological quality.ConclusionAppropriately designed exercise interventions enhance QOL for cancer survivors and this pattern is especially evident for women. Limitations are discussed.

The HIV-Knowledge Questionnaire: Development and Evaluation of a Reliable, Valid, and Practical Self-Administered Questionnaire

We have developed and evaluated a self-administered questionnaire of knowledge about human immunodeficiency virus (HIV) infection for use in program evaluation. Formative work led to the development of the 62-item HIV-Knowledge Questionnaire (HIV-K-Q), which was administered to 409 women and 227 men. Item analyses resulted in the deletion of 17 items that were either too easy or did not correlate well with the total score. Factor analysis on the remaining 45 items resulted in a single factor labeled HIV Knowledge. The generalizability of this one-factor solution was confirmed with data from 285 women and 76 men. Reliability analyses revealed that the HIV-K-Q is internally consistent (alpha = .91) and stable over 1-week (r = .83), 2-week (r = .91), and 12-week (r = .90) intervals. Evidence for the validity of the HIV-K-Q was assembled using known groups and treatment outcome analyses. Additional evidence emerged from analyses that revealed associations between scores on the HIV-K-Q and two related knowledge measures, and between HIV-K-Q scores and level of educational attainment. Discriminant evidence was obtained through nonsignificant relationships between the HIV-K-Q and potentially biasing constructs, including social desirability. The HIV-K-Q requires a sixth-grade education, and 7 min to complete. The HIV-K-Q is a reliable, valid, and practical measure of HIV-related knowledge that can be used with low-literacy adults.