M. Meta-Analysis

2021 ◽  
pp. 163-165
Author(s):  
Noémie Laurens
Keyword(s):  
Literature Review ◽  
Empirical Research ◽  
Effect Size ◽  
Meta Analysis ◽  
Research Synthesis ◽  
Effect Sizes ◽  
Primary Research ◽  
Unit Of Analysis ◽  
Research Studies

This chapter illustrates meta-analysis, which is a specific type of literature review, and more precisely a type of research synthesis, alongside traditional narrative reviews. Unlike in primary research, the unit of analysis of a meta-analysis is the results of individual studies. And unlike traditional reviews, meta-analysis only applies to: empirical research studies with quantitative findings hat are conceptually comparable and configured in similar statistical forms. What further distinguishes meta-analysis from other research syntheses is the method of synthesizing the results of studies — i.e. the use of statistics and, in particular, of effect sizes. An effect size represents the degree to which the phenomenon under study exists.

Can Reliance be Placed on a Single Meta-Analysis?

1990 ◽  
Vol 24 (3) ◽  
pp. 405-415 ◽  
Author(s):  
Nathaniel McConaghy
Keyword(s):  
Literature Review ◽  
Effect Size ◽  
Meta Analysis ◽  
Statistical Significance ◽  
Effect Sizes ◽  
Control Groups ◽  
Consistent Finding ◽  
Placebo Controls ◽  
Effect Of Treatment ◽  
Meta Analyses

Meta-analysis replaced statistical significance with effect size in the hope of resolving controversy concerning evaluation of treatment effects. Statistical significance measured reliability of the effect of treatment, not its efficacy. It was strongly influenced by the number of subjects investigated. Effect size as assessed originally, eliminated this influence but by standardizing the size of the treatment effect could distort it. Meta-analyses which combine the results of studies which employ different subject types, outcome measures, treatment aims, no-treatment rather than placebo controls or therapists with varying experience can be misleading. To ensure discussion of these variables meta-analyses should be used as an aid rather than a substitute for literature review. While meta-analyses produce contradictory findings, it seems unwise to rely on the conclusions of an individual analysis. Their consistent finding that placebo treatments obtain markedly higher effect sizes than no treatment hopefully will render the use of untreated control groups obsolete.

scholarly journals A Statistical Method for Synthesizing Meta-Analyses

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Liansheng Larry Tang ◽  
Michael Caudy ◽  
Faye Taxman
Keyword(s):  
Statistical Method ◽  
Effect Size ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Weighted Mean ◽  
Summary Effect ◽  
Different Types ◽  
Meta Analyses ◽  
Size Estimates ◽  
Similar Search

Multiple meta-analyses may use similar search criteria and focus on the same topic of interest, but they may yield different or sometimes discordant results. The lack of statistical methods for synthesizing these findings makes it challenging to properly interpret the results from multiple meta-analyses, especially when their results are conflicting. In this paper, we first introduce a method to synthesize the meta-analytic results when multiple meta-analyses use the same type of summary effect estimates. When meta-analyses use different types of effect sizes, the meta-analysis results cannot be directly combined. We propose a two-step frequentist procedure to first convert the effect size estimates to the same metric and then summarize them with a weighted mean estimate. Our proposed method offers several advantages over existing methods by Hemming et al. (2012). First, different types of summary effect sizes are considered. Second, our method provides the same overall effect size as conducting a meta-analysis on all individual studies from multiple meta-analyses. We illustrate the application of the proposed methods in two examples and discuss their implications for the field of meta-analysis.

scholarly journals Changes of Ankle Dorsiflexion Using Compression Tissue Flossing: A Systematic Review and Meta-Analysis

2020 ◽  
pp. 1-9
Author(s):  
Devin S. Kielur ◽  
Cameron J. Powden
Keyword(s):  
Confidence Interval ◽  
Range Of Motion ◽  
Effect Size ◽  
Evidence Synthesis ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Lower Extremity Injury ◽  
Level Of Evidence ◽  
Physically Active ◽  
Evidence Database

Context: Impaired dorsiflexion range of motion (DFROM) has been established as a predictor of lower-extremity injury. Compression tissue flossing (CTF) may address tissue restrictions associated with impaired DFROM; however, a consensus is yet to support these effects. Objectives: To summarize the available literature regarding CTF on DFROM in physically active individuals. Evidence Acquisition: PubMed and EBSCOhost (CINAHL, MEDLINE, and SPORTDiscus) were searched from 1965 to July 2019 for related articles using combination terms related to CTF and DRFOM. Articles were included if they measured the immediate effects of CTF on DFROM. Methodological quality was assessed using the Physiotherapy Evidence Database scale. The level of evidence was assessed using the Strength of Recommendation Taxonomy. The magnitude of CTF effects from pre-CTF to post-CTF and compared with a control of range of motion activities only were examined using Hedges g effect sizes and 95% confidence intervals. Randomeffects meta-analysis was performed to synthesize DFROM changes. Evidence Synthesis: A total of 6 studies were included in the analysis. The average Physiotherapy Evidence Database score was 60% (range = 30%–80%) with 4 out of 6 studies considered high quality and 2 as low quality. Meta-analysis indicated no DFROM improvements for CTF compared with range of motion activities only (effect size = 0.124; 95% confidence interval, −0.137 to 0.384; P = .352) and moderate improvements from pre-CTF to post-CTF (effect size = 0.455; 95% confidence interval, 0.022 to 0.889; P = .040). Conclusions: There is grade B evidence to suggest CTF may have no effect on DFROM when compared with a control of range of motion activities only and results in moderate improvements from pre-CTF to post-CTF. This suggests that DFROM improvements were most likely due to exercises completed rather than the band application.

Effect Sizes: Conventional Choices and Calculations

2013 ◽  
Author(s):  
Michael S. Rosenberg ◽  
Hannah R. Rothstein ◽  
Jessica Gurevitch
Keyword(s):  
Critical Point ◽  
Effect Size ◽  
Evolutionary Biology ◽  
Meta Analysis ◽  
Statistical Parameter ◽  
Effect Sizes ◽  
Common Effect ◽  
Inference Methods ◽  
Conventional Effect ◽  
Estimate Effect Size

One of the fundamental concepts in meta-analysis is that of the effect size. An effect size is a statistical parameter that can be used to compare, on the same scale, the results of different studies in which a common effect of interest has been measured. This chapter describes the conventional effect sizes most commonly encountered in ecology and evolutionary biology, and the types of data associated with them. While choice of a specific measure of effect size may influence the interpretation of results, it does not influence the actual inference methods of meta-analysis. One critical point to remember is that one cannot combine different measures of effect size in a single meta-analysis: once you have chosen how you are going to estimate effect size, you need to use it for all of the studies to be analyzed.

scholarly journals A-17 Category Test performance in individuals with alcohol versus methamphetamine dependence

2019 ◽  
Vol 34 (6) ◽  
pp. 876-876
Author(s):  
A Walker ◽  
A Hauson ◽  
S Sarkissians ◽  
A Pollard ◽  
C Flora-Tostado ◽  
...  
Keyword(s):  
Effect Size ◽  
Test Performance ◽  
Neuropsychological Functioning ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Significant Heterogeneity ◽  
Category Test ◽  
Methamphetamine Dependence ◽  
Significant Difference ◽  
Axis I

Abstract Objective The Category Test (CT) has consistently been found to be sensitive at detecting the effects of alcohol on the brain. However, this test has not been as widely used in examining the effects of methamphetamine. The current meta-analysis compared effect sizes of studies that have examined performance on the CT in alcohol versus methamphetamine dependent participants. Data selection Three researchers independently searched nine databases (e.g., PsycINFO, Pubmed, ProceedingsFirst), extracted required data, and calculated effect sizes. Inclusion criteria identified studies that had (a) compared alcohol or methamphetamine dependent groups to healthy controls and (b) matched groups on either age, education, or IQ (at least 2 out of 3). Studies were excluded if participants were reported to have Axis I diagnoses (other than alcohol or methamphetamine dependence) or comorbidities known to impact neuropsychological functioning. Sixteen articles were coded and analyzed for the current study. Data synthesis Alcohol studies showed a large effect size (g = 0.745, p < 0.001) while methamphetamine studies evidenced a moderate effect size (g = 0.406, p = 0.001); both without statistically significant heterogeneity (I2 = 0). Subgroup analysis revealed a statistically significant difference between the effect sizes from alcohol versus methamphetamine studies (Q-between = 5.647, p = 0.017). Conclusions The CT is sensitive to the effects of both alcohol and methamphetamine and should be considered when examining dependent patients who might exhibit problem solving, concept formation, and set loss difficulties in everyday living.

Test Frequency, Stakes, and Feedback in Student Achievement: A Meta-Analysis

2019 ◽  
Vol 43 (3-4) ◽  
pp. 111-151 ◽  
Author(s):  
Richard P. Phelps
Keyword(s):  
Student Achievement ◽  
Early Childhood ◽  
Effect Size ◽  
English Language ◽  
Variance Estimation ◽  
Meta Analysis ◽  
The United States ◽  
Research Literature ◽  
Effect Sizes ◽  
Test Frequency

Background: Test frequency, stakes associated with educational tests, and feedback from test results have been identified in the research literature as relevant factors in student achievement. Objectives: Summarize the separate and joint contribution to student achievement of these three treatments and their interactions via multivariable meta-analytic techniques using a database of English-language studies spanning a century (1910–2010), comprising 149 studies and 509 effect size estimates. Research design: Analysis employed robust variance estimation. Considered as potential moderators were hundreds of study features comprising various test designs and test administration, demographic, and source document characteristics. Subjects: Subjects were students at all levels, from early childhood to adult, mostly from the United States but also eight other countries. Results: We find a summary effect size of 0.84 for the three treatments collectively. Further analysis suggests benefits accrue to the incremental addition of combinations of testing and feedback or stakes and feedback. Moderator analysis shows higher effect sizes associated with the following study characteristics: more recent year of publication, summative (rather than formative) testing, constructed (rather than selected) item response formats, alignment of subject matter between pre- and posttests, and recognition/recall (rather than core subjects, art, or physical education). Conversely, lower effect sizes are associated with postsecondary students (rather than early childhood–upper secondary), special education population, larger study population, random assignment (rather than another sampling method), use of shadow test as outcome measure, designation of individuals (rather than groups) as units of analysis, and academic (rather than corporate or government) research.

Action observation therapy for improving arm function, walking ability, and daily activity performance after stroke: a systematic review and meta-analysis

2019 ◽  
Vol 33 (8) ◽  
pp. 1277-1285 ◽  
Author(s):  
Tzu-Hsuan Peng ◽  
Jun-Ding Zhu ◽  
Chih-Chi Chen ◽  
Ruei-Yi Tai ◽  
Chia-Yi Lee ◽  
...  
Keyword(s):  
Effect Size ◽  
Action Observation ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Gait Velocity ◽  
Walking Ability ◽  
Stroke Patients ◽  
Large Effect Size ◽  
Subgroup Analyses ◽  
Activity Performance

Objective:This study was to investigate the effectiveness of action observation therapy on arm and hand motor function, walking ability, gait performance, and activities of daily living in stroke patients.Design:Systematic review and meta-analysis of randomized controlled trials.Data sources:Searches were completed in January 2019 from electronic databases, including PubMed, Scopus, the Cochrane Library, and OTseeker.Review methods:Two independent reviewers performed data extraction and evaluated the study quality by the PEDro scale. The pooled effect sizes on different aspects of outcome measures were calculated. Subgroup analyses were performed to examine the impact of stroke phases on treatment efficacy.Results:Included were 17 articles with 600 patients. Compared with control treatments, the action observation therapy had a moderate effect size on arm and hand motor outcomes (Hedge’s g = 0.564; P < 0.001), a moderate to large effect size on walking outcomes (Hedge’s g = 0.779; P < 0.001), a large effect size on gait velocity (Hedge’s g = 0.990; P < 0.001), and a moderate to large effect size on activities of daily function (Hedge’s g = 0. 728; P = 0.004). Based on subgroup analyses, the action observation therapy showed moderate to large effect sizes in the studies of patients with acute/subacute stroke or those with chronic stroke (Hedge’s g = 0.661 and 0.783).Conclusion:This review suggests that action observation therapy is an effective approach for stroke patients to improve arm and hand motor function, walking ability, gait velocity, and daily activity performance.

scholarly journals Nutraceutical supplements in management of pain and disability in osteoarthritis: a systematic review and meta-analysis of randomized clinical trials

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dawood Aghamohammadi ◽  
Neda Dolatkhah ◽  
Fahimeh Bakhtiari ◽  
Fariba Eslamian ◽  
Maryam Hashemian
Keyword(s):  
Pain Intensity ◽  
Physical Function ◽  
Random Effects ◽  
Effect Size ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Cochrane Library ◽  
Random Effects Model ◽  
Womac Index ◽  
Pain Subscale

AbstractThis study designed to evaluate the effect of nutraceutical supplementation on pain intensity and physical function in patients with knee/hip OA. The MEDLINE, Web of Science, Cochrane Library, Scopus, EMBASE, Google Scholar, Science direct, and ProQuest in addition to SID, Magiran, and Iranmedex were searched up to March 2020. Records (n = 465) were screened via the PICOS criteria: participants were patients with hip or knee OA; intervention was different nutritional supplements; comparator was any comparator; the outcome was pain intensity (Visual analogue scale [VAS]) and physical function (Western Ontario and McMaster Universities Arthritis [WOMAC] index); study type was randomized controlled trials. The random effects model was used to pool the calculated effect sizes. The standardized mean difference (SMD) of the outcome changes was considered as the effect size. The random effects model was used to combine the effect sizes. Heterogeneity between studies was assessed by Cochran's (Q) and I2 statistics. A total of 42 RCTs were involved in the meta-analysis. Nutritional supplementation were found to improve total WOMAC index (SMD = − 0.23, 95% CI − 0.37 to − 0.08), WOMAC pain (SMD = − 0.36, 95% CI − 0.62 to − 0.10) and WOMAC stiffness (SMD = − 0.47, 95% CI − 0.71 to − 0.23) subscales and VAS (SMD = − 0.79, 95% CI − 1.05 to − 0.05). Results of subgroup analysis according to the supplementation duration showed that the pooled effect size in studies with < 10 months, 10–20 months and > 20 months supplementation duration were 0.05, 0.27, and 0.36, respectively for WOMAC total score, 0.14, 0.55 and 0.05, respectively for WOAMC pain subscale, 0.59, 0.47 and 0.41, respectively for WOMAC stiffness subscale, 0.05, 0.57 and 0.53, respectively for WOMAC physical function subscale and 0.65, 0.99 and 0.12, respectively for VAS pain. The result suggested that nutraceutical supplementation of patients with knee/hip OA may lead to an improvement in pain intensity and physical function.

Effect of exercise training on quality of life in multiple sclerosis: a meta-analysis

2008 ◽  
Vol 14 (1) ◽  
pp. 129-135 ◽  
Author(s):  
R.W. Motl ◽  
J.L. Gosney
Keyword(s):  
Quality Of Life ◽  
Multiple Sclerosis ◽  
Exercise Training ◽  
Effect Size ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Training Interventions ◽  
Manual Search ◽  
Exercise Stimulus

Using meta-analytic procedures, this study examined the overall effect of exercise training interventions on quality of life (QOL) among individuals with multiple sclerosis (MS). We searched MEDLINE, PSYCHINFO and CURRENT CONTENTS PLUS for the period of 1960 to November 2006 using the key words exercise, physical activity and physical fitness in conjunction with QOL and MS. We further conducted a manual search of bibliographies of the retrieved papers as well as literature reviews and contacted study authors about additional studies. Twenty-five journal articles were located and reviewed, and only 13 provided enough data to compute effect sizes expressed as Cohen's d. One hundred and nine effect sizes were retrieved from the 13 studies with 484 MS participants and yielded a weighted mean effect size of g = 0.23 (95% CI = 0.15, 0.31). There were larger effects associated with MS-specific measures of QOL and fatigue as an index of QOL. The nature of the exercise stimulus further influenced the magnitude of the mean effect size. The cumulative evidence supports that exercise training is associated with a small improvement in QOL among individuals with MS. Multiple Sclerosis 2008; 14: 129—135. http://msj.sagepub.com

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