Weighted Mean Effect Research Articles

Clinical Effect of Naturally Random Allocation to Lower Systolic Blood Pressure Beginning Before the Development of Hypertension

Systolic blood pressure (SBP) rises approximately linearly with age in most societies. The cause of this rise is unclear. We tested the hypothesis that SBP is causally associated with the rate of rise in SBP with age by evaluating the effect of 12 polymorphisms associated with lower SBP on the age-related rate of rise in SBP in a series of meta-regression analyses involving ≤199 477 participants in 63 studies. We then evaluated the effect of these polymorphisms on the odds of coronary heart disease in 22,223 case and 64,762 control subjects and compared it with the effect of lower SBP observed in both prospective cohort studies and blood pressure-lowering randomized trials. All 12 polymorphisms were associated with both lower SBP and a slower age-related rise in SBP. The weighted mean effect of these 12 polymorphisms was associated with a 0.32-mm Hg lower SBP (P=1.79×10(-7)) and a 0.093-mm Hg/decade slower age-related rise in SBP (P=3.05×10(-5)). The effect of long-term exposure to lower SBP on coronary heart disease mediated by these polymorphisms was 2-fold greater than that observed in prospective cohort studies (P=0.006) and 3-fold greater than that observed in short-term blood pressure treatment trials (P=0.001). We conclude therefore that SBP seems to be causally associated with the rate of rise in SBP with age and has a cumulative effect on the risk of coronary heart disease.

The Effect of Response Shift on Quality of Life among Cancer Patients: A Systematic Review

Aims and Objectives: To scrutinize the evidence of response shift effect on published quality of life (QOL) studies investigating the patient-reported outcome to obtain accuracy data as evaluating clinical practice. Background: People may alter their internal standards, known as response shift, when they experience changes in their health status. This phenomenon can falsify patient-reported measures, and has gained increasing attention recently in explaining research paradoxical findings. Nevertheless a rigorous evidence-base about this effect on cancer patients QOL is lacking. Design: A systematic review was carried out under adhered to the guideline of the Quality of Reporting of Meta-Analyses. Methods: A comprehensive search was conducted on seven English and Chinese databases to identify and collect studies focus on cancer patients QOL. Methodological quality assessment was performed to assess the strength of evidence. Results: Using pre-determined keywords, 584 relevant titles were identified. Eventually 14 papers satisfied the inclusion criteria and entered the quality assessment stage. All the articles were written in English and published between 1996 and 2013. A majority of the studies used the then-test method, which is also known as the retrospective pretest-posttest design method. The weighted mean effect size (WMES) was 0.47 (95% CI 0.31 to 0.63). Using data from the six studies for assessing then-test/pre-test comparison on the outcome measure fatigue, the WMES was -0.21 (95% CI -0.32 to -0.10). Conclusion: The alternation of self-internal standard occurs when cancer patients evaluated their QOL over a period of time. Relevance to clinical practice: This review emphasizes the need for a more sensitive approach to inspect the clinical impact of response shift by measuring changes in QOL. Patients’ adaptation to the disease can then be more precisely acquired.

A Meta-Analysis of Empirically Tested School-Based Dating Violence Prevention Programs

Teen dating violence prevention programs implemented in schools and empirically tested were subjected to meta-analysis. Eight studies met criteria for inclusion, consisting of both within and between designs. Overall, the weighted mean effect size (ES) across studies was significant, ES r = .11; 95% confidence interval (CI) = [.08, .15], p < .0001, showing an overall positive effect of the studied prevention programs. However, 25% of the studies showed an effect in the negative direction, meaning students appeared to be more supportive of dating violence after participating in a dating violence prevention program. This heightens the need for thorough program evaluation as well as the need for decision makers to have access to data about the effectiveness of programs they are considering implementing. Further implications of the results and recommendations for future research are discussed.

A meta-analysis of the effects of curriculum reconstruction

이 연구는 교육과정 재구성의 학습효과에 대한 일반화된 결론을 도출하고, 교육과정 재구성의 학습효과에 영향을 미치는 조절변인을 발견함으로써, 단위 학교와 교사들에게 교육과정 재구성에 대한 시사점을 제공하는데 그 목적이 있다. 이 연구에서는 1997년부터 2013년까지 교육과정 재구성의 학습효과를 검증한 석사학위 논문 28편의 자료를 선정하고, 이 중에서 39개의 개별 효과 크기를 산출하였다. 이 연구의 결과는 다음과 같다. 첫째, 교육과정 재구성의 학습효과는 중간 정도의 효과(d+=.44, 95% CI .38-.51, U3=67.16)가 있었다. 둘째, 교육과정 재구성의 학습효과는 인지적 영역(d+=.45, U3=67.23, p .05)에서는 유의하지 않았다. 셋째, 교육과정재구성의 학습효과에 영향을 주는 조절변인은 학교급, 교과, 개발 자료 활용 변인이었다. 이 연구의 시사점은 다음과 같다. 첫째, 교육과정 재구성은 학생들의 인지적, 정의적 영역의 학습에 효과적이라는 것이다. 둘째, 단위 학교와 교사가 교육과정 재구성을 계획하고 실행할 때에는 상위 수준의 교육과정, 학습자, 교사, 사회의 특성을 종합적으로 고려해야 한다는 것이다. 셋째, 교육과정 재구성의 학습효과를 촉진시킬 수 있는 교육과정자료가 단위 학교에 개발 및 보급되어야 하고, 교육과정 재구성에 대한 교원의 전문성을 향상시킬 수 있는 물적·인적 자원이 제공되어야 한다.

Effect of prior exercise on postprandial lipemia: an updated quantitative review

Reducing postprandial triglycerides (TG) can lower the risk for cardiovascular disease. The purpose of this study was to perform a meta-analytic review of the literature to estimate the effect of prior exercise on postprandial lipemia. A total of 121 effects were found from 76 studies for the total TG response and 70 effects from 44 studies for the incremental area under the curve (iAUC) TG response. The weighted mean effect was moderate for the total TG response, Cohen's d = -0.60 (P < 0.0001), and for the iAUC response, Cohen's d = -0.59 (P < 0.0001). Moderator analysis revealed women exhibited a larger reduction (P < .01) in the total TG response following exercise (d = -0.96) than men (d = -0.57); high-intensity interval training induced a larger reduction (P < .05) in the iAUC response (d = -1.49) than aerobic (d = -0.58) or resistance (d = -0.13) exercise, and participants maintaining an energy deficit following exercise exhibited a greater reduction in the iAUC response (d = -0.67) compared with participants in energy balance (d = -0.28). We conclude that prior acute exercise reduces postprandial lipemia, with the magnitude of effect influenced by sex, type of exercise, and energy deficit following exercise.

Physical activity intervention studies and their relationship to body composition in healthy women.

Engaging in regular physical activity is a key component for maintaining a healthy weight and preventing overweight and obesity. Obesity continues to be a concern globally, especially for women, and women are less physically active than men. This systematic review examined current research on physical activity interventions designed for healthy community dwelling women and assessed the effects of those interventions on physical activity and body composition. Three author-developed data collection tools were used to extract and examine study variables. For studies with suitable data, effect sizes were obtained. The initial search identified 1,406 titles published between 2000 and 2012, of which 40 randomized clinical trials met inclusion criteria. Of these 40 studies, 16 had a physical activity intervention that did not have a diet component and 24 had a physical activity intervention along with a diet component. The overall weighted mean effect was d = .21, 95% CI [0.06, 0.36] for physical activity outcomes (n = 18 studies) and d = -.16, 95% CI [-0.22, -0.09] for body composition outcomes (n = 24 studies). Both physical activity interventions without and with a diet component were effective in promoting physical activity and improving body composition. Physical activity interventions without a diet component were more effective than physical activity interventions with a diet component at promoting physical activity. The most effective interventions need to be adapted for dissemination into practice.

Cooperative Learning and Literacy: A Meta-Analytic Review

We conducted a meta-analysis on the effectiveness of cooperative and collaborative learning to support enhanced literacy outcomes. Interventions considered were provided in regular education settings (i.e., not pull-out instruction) with students from Grades 2 through 12. Reviewing more than 30 years of literacy research, we located 18 intervention studies with 29 study cohorts. Included studies primarily used standardized assessments to report on students’ reading, vocabulary, or comprehension achievement, which we analyzed separately. Overall, students had significantly higher literacy achievement scores when instructional interventions utilized cooperative and collaborative activity structures. The overall weighted mean effect sizes ranged from 0.16 to 0.22 (p < .01) with more than 94% of the point estimates being positive. Because cooperative or collaborative learning was always one of multiple intervention components, it was impossible to estimate the unique, added effects of cooperative/collaborative learning. Although the small number of eligible studies precludes any claims about the effectiveness of specific forms of grouping and the circumstances under which programs have more impact, our findings suggest that cooperative and collaborative grouping was a core component of effective literacy interventions, particularly at the elementary level.

Batterer intervention programmes: A meta-analytic review of effectiveness

A meta-analysis of the state-of-the-art on the efficacy of batterer treatment programmes was conducted from the year 1975 to 2013. A total of 19 Spanish and English language research articles were retrieved yielding 49 effect sizes from a sample of 18,941 batterers. The results revealed that the recidivism rate as measured by couple reports (CR) was significantly higher than the rate based on official reports (OR), since the recidivism as measured by OR is underestimated. Overall, treatment showed a non significant positive weighted mean effect, δ=0.41. Nevertheless, the counternull effect size, EScounternull =0.82, suggested a null effect was as probable as a treatment efficacy rate of 38%. The intervention type was not a significant moderator of recidivism, but the counternull effect sizes, EScounternull = 0.82 and 0.94, revealed an efficacy rate of 38% and 42% based on ORs, for Duluth Model and behavioral-cognitive treatment, respectively. The long-term treatment interventions had a significantly positive medium effect size, δ=0.49. The implications of these findings for the design and assessment of future intervention programmes are discussed.

Mental Health and Obesity: A Meta-Analysis

The relationship between obesity and psychological distress is not clear because research conducted so far is not conclusive, with some studies finding that obese people report less mental health than normal-weight individuals, whilst others find that obesity may work as a protective factor that prevents people with weight problems from developing mental health issues. In this meta-analysis we review research that compares the mental health (measured with SF-36) of class I obese people (Body Mass Index between 30 and 34.99) with normal weight people (Body Mass Index between 18 and 24.99) in non-clinical adult populations. The meta-analysis conducted assumed a random-effects model and a weighted mean effect size was calculated (d), together with its statistical significance and confidence interval. Results reveal that obese women report less mental health than normal weight females (d = −.26) but that obese men show more mental health than normal weight individuals (d = .62). The results give support to the so-called “Jolly Fat” hypothesis.

The Construct and Criterion Validity of the Mini-CEX

To conduct a meta-analysis of published studies to determine the construct and criterion validity of the mini-clinical evaluation exercise (mini-CEX) to measure clinical performance. The authors included all peer-reviewed studies published from 1995 to 2012 that reported the relationship between participants' performance on the mini-CEX and on other standardized academic and clinical performance measures. Moderator variables and performance and standardized exam measures were extracted and reviewed independently using a standardized coding protocol. Performance measures from 11 studies were identified. A random-effects model of weighted mean effect size differences (d) resulted in: (1) construct validity coefficients for the mini-CEX on the trainees' performance across different residency year levels ranging from d=0.25 (95% confidence intervals [CI]: 0.04-0.46) to d=0.50 (95% CI: 0.31-0.70), and (2) concurrent validity coefficients for the mini-CEX based on personnel ratings ranging from d=0.23 (95% CI: 0.04-0.50) to d=0.50 (95% CI: 0.34-0.65). Also, a random-effects model of weighted correlation effect size differences (r) resulted in predictive validity coefficients for the mini-CEX on trainees' performance across different standardized measures ranging from r=0.26 (95% CI: 0.16-0.35) to r=0.85 (95% CI: 0.47-0.96). The construct and criterion validity of the mini-CEX was supported by small to large effect size differences based on measures between trainees' achievement and clinical skills performance, indicating that it is an important instrument for the direct observation of trainees' clinical performance.

Recent developments in the experimental investigation of the illusion of control. A meta‐analytic review

AbstractThe present study analyzes recent developments in the experimental investigation of the illusion of control by using the methods of meta‐analysis. The aim of the study was to estimate the effect sizes associated with different factors thought to induce the illusion of control considering different conceptualizations of the phenomenon. The overall weighted mean effect size (D) was.62, with the 95% confidence interval about the mean.49 to.75. Generally, experiments tend to obtain moderate to large effect sizes, and the illusion of control is constantly present as an effect of several situational and psychological factors. Nevertheless, the large heterogeneity of the studies in terms of dependent measures suggests that the underlying phenomena can be of a different nature.

The Adverse Effect of Fluoride on Children’s Intelligence: A Systematic Review

The authors conducted a systematic review on published studies to date to investigate the effect of fluoride exposure on children’s intelligence quotient (IQ) scores. PSYCHINFO, Web of Science, MEDLINE, SCI, and the China National Knowledge Infrastructure (CNKI) search engines were employed for all documents published up to 2012, in English and in Chinese. In total, 38 studies of fluoride exposure and children’s scores on IQ tests were included in this review. The weighted mean effect size (WMES) on children’s IQ scores between higher and lower regions of fluoride exposure was -.46 (CI 95% -.57 to -.35; p<.001) equivalent to 6.9 IQ points. Sensitivity analyses showed that after excluding studies that had other elements contaminations, the adverse effects of fluoride exposure on children’s intelligence remained to be significant. Further, six of the studies reported significant negative correlations between fluoride in the body and intelligence. The evidence suggests that fluoride in drinking water is a serious public health hazard.

Student evaluations of teaching: combining the meta-analyses and demonstrating further evidence for effective use

There is a plethora of research on student evaluations of teaching (SETs) regarding their validity, susceptibility to bias, practical use and effective implementation. Given that there is not one study summarising all these domains of research, a comprehensive overview of SETs was conducted by combining all prior meta-analyses related to SETs. Eleven meta-analyses were identified, and nine meta-analyses covering 193 studies were included in the analysis, which yielded a small-to-medium overall weighted mean effect size (r = .26) between SETs and the variables studied. Findings suggest that SETs appear to be valid, have practical use that is largely free from gender bias and are most effective when implemented with consultation strategies. Research, teaching and policy implications are discussed.

The effects of ‘ecstasy’ (MDMA) on visuospatial memory performance: findings from a systematic review with meta‐analyses

To review, with meta-analyses where appropriate, performance differences between ecstasy (3,4-methylenedioxymethamphetamine) users and non-users on a wider range of visuospatial tasks than previously reviewed. Such tasks have been shown to draw upon working memory executive resources. Abstract databases were searched using the United Kingdom National Health Service Evidence Health Information Resource. Inclusion criteria were publication in English language peer-reviewed journals and the reporting of new findings regarding human ecstasy-users' performance on visuospatial tasks. Data extracted included specific task requirements to provide a basis for meta-analyses for categories of tasks with similar requirements. Fifty-two studies were identified for review, although not all were suitable for meta-analysis. Significant weighted mean effect sizes indicating poorer performance by ecstasy users compared with matched controls were found for tasks requiring recall of spatial stimulus elements, recognition of figures and production/reproduction of figures. There was no evidence of a linear relationship between estimated ecstasy consumption and effect sizes. Given the networked nature of processing for spatial and non-spatial visual information, future scanning and imaging studies should focus on brain activation differences between ecstasy users and non-users in the context of specific tasks to facilitate identification of loci of potentially compromised activity in users.

Formative Assessment: A Meta-Analysis and a Call for Research

An effect size of about .70 (or .40–.70) is often claimed for the efficacy of formative assessment, but is not supported by the existing research base. More than 300 studies that appeared to address the efficacy of formative assessment in grades K-12 were reviewed. Many of the studies had severely flawed research designs yielding uninterpretable results. Only 13 of the studies provided sufficient information to calculate relevant effect sizes. A total of 42 independent effect sizes were available. The median observed effect size was .25. Using a random effects model, a weighted mean effect size of .20 was calculated. Moderator analyses suggested that formative assessment might be more effective in English language arts (ELA) than in mathematics or science, with estimated effect sizes of .32, .17, and .09, respectively. Two types of implementation of formative assessment, one based on professional development and the other on the use of computer-based formative systems, appeared to be more effective than other approaches, yielding mean effect size of .30 and .28, respectively. Given the wide use and potential efficacy of good formative assessment practices, the paucity of the current research base is problematic. A call for more high-quality studies is issued.

Gender differences in self-estimates of general, mathematical, spatial and verbal intelligence: Four meta analyses

Four meta-analyses were conducted to examine the magnitude of sex differences in self-estimates of general, mathematical/logical, spatial and verbal abilities. For all but verbal ability males gave significantly higher self-estimates than did females. The weighted mean effect size d for general intelligence was .37, for mathematical .44, for spatial .43 and for verbal .07. As these were significantly heterogeneous, homogeneity analysis was performed to identify moderating factors. These included age, instruction type, country and dominating author's gender. The outcomes were discussed in terms of possible causes of this phenomenon and some concerns about the interpretation of the results were raised.

Meta-analysis of facial affect recognition difficulties after traumatic brain injury.

Difficulties in communication and social relationships present a formidable challenge for many people after traumatic brain injury (TBI). These difficulties are likely to be partially attributable to problems with emotion perception. Mounting evidence shows facial affect recognition to be particularly difficult after TBI. However, no attempt has been made to systematically estimate the magnitude of this problem or the frequency with which it occurs. A meta-analysis is presented examining the magnitude of facial affect recognition difficulties after TBI. From this, the frequency of these impairments in the TBI population is estimated. Effect sizes were calculated from 13 studies that compared adults with moderate to severe TBI to matched healthy controls on static measures of facial affect recognition. The studies collectively presented data from 296 adults with TBI and 296 matched controls. The overall weighted mean effect size for the 13 studies was -1.11, indicating people with TBI on average perform about 1.1 SD below healthy peers on measures of facial affect recognition. Based on estimation of the TBI population standard deviation and modeling of likely distribution shape, it is estimated that between 13% and 39% of people with moderate to severe TBI may have significant difficulties with facial affect recognition, depending on the cut-off criterion used. This is clearly an area that warrants attention, particularly examining techniques for the rehabilitation of these deficits.

Overview of Meta-Analyses on Early Intensive Behavioral Intervention for Young Children with Autism Spectrum Disorders

This paper presents an overview of 5 meta-analyses of early intensive behavioral intervention (EIBI) for young children with autism spectrum disorders (ASDs) published in 2009 and 2010. There were many differences between meta-analyses, leading to different estimates of effect and overall conclusions. The weighted mean effect sizes across meta-analyses for IQ and adaptive behavior ranged from g=.38-1.19 and g=.30-1.09, respectively. Four of five meta-analyses concluded EIBI was an effective intervention strategy for many children with ASDs. A discussion highlighting potential confounds and limitations of the meta-analyses leading to these discrepancies and conclusions about the efficacy of EIBI as an intervention for young children with ASDs are provided.

Prevalence of comorbid disorders in problem and pathological gambling: systematic review and meta‐analysis of population surveys

This paper reviews evidence pertaining to the prevalence of common comorbid disorders, including alcohol use disorder, depression, substance use disorders, nicotine dependence, anxiety disorders and antisocial personality disorder, in population-representative samples of problem and pathological gamblers. A systematic search was conducted for peer-reviewed and unpublished articles reported between 1 January 1998 and 20 September 2010. Only studies which examined the prevalence of comorbid conditions in problem and/or pathological gamblers from a general population sample using randomized sampling methods and standardized measurement tools were included. Meta-analysis techniques were then performed to synthesize the included studies and estimate the weighted mean effect size and heterogeneity across studies. Eleven eligible studies were identified from the literature. Results from across the studies indicated that problem and pathological gamblers had high rates of other comorbid disorders. The highest mean prevalence was for nicotine dependence (60.1%), followed by a substance use disorder (57.5%), any type of mood disorder (37.9%) and any type of anxiety disorder (37.4%). However, there was evidence of moderate heterogeneity across studies, suggesting that rate estimates do not necessarily converge around a single population figure, and that weighted means should be interpreted with caution. Problem and pathological gamblers experience high levels of other comorbid mental health disorders and screening for comorbid disorders upon entering treatment for gambling problems is recommended. Further research is required to explore the underlying causes of variability observed in the prevalence estimates.

A Meta-analytic Review of the Role of Child Anxiety Sensitivity in Child Anxiety

Conflicting findings exist regarding (1) whether anxiety sensitivity (AS) is a construct distinct from anxiety in children and (2) the specific nature of the role of AS in child anxiety. This study uses meta-analytic techniques to (1) determine whether youth (ages 6-18years) have been reported to experience AS, (2) examine whether AS differentiates anxiety disordered youth from youth without diagnoses, and (3) ascertain whether AS distinguishes youth with panic disorder from those with other anxiety disorders. The weighted mean effect size analyses included 15 studies and 6,579 participants. Results suggested positive correlational relationships between AS and anxiety for children (r = 0.26) and adolescents (r = 0.36) and higher levels of AS for anxiety disordered youth than non-clinical youth (d = 0.64). Findings tentatively suggested higher levels of AS for youth with panic disorder than youth diagnosed with other anxiety disorders. Implications and future directions in the research of child AS are discussed.