scholarly journals An assessment of statistical methods for non-independent data in ecological meta-analyses: Comment

2021 ◽  
Author(s):  
Shinichi Nakagawa ◽  
Alistair M Senior ◽  
Wolfgang Viechtbauer ◽  
Daniel W.A. Noble
Keyword(s):  
Random Effects ◽  
Effect Size ◽  
Variance Estimation ◽  
Meta Analysis ◽  
Estimation Method ◽  
Random Effects Model ◽  
Step Method ◽  
Robust Variance ◽  
Robust Variance Estimation ◽  
Meta Analyses

Recently, Song et al. (2020) conducted a simulation study using different methods to deal with non-independence resulting from effect sizes originating from the same paper – a common occurrence in ecological meta-analyses. The main methods that were of interest in their simulations were: 1) a standard random-effects model used in combination with a weighted average effect size for each paper (i.e., a two-step method), 2) a standard random-effects model after randomly choosing one effect size per paper, 3) a multilevel (hierarchical) meta-analysis model, modelling paper identity as a random factor, and 4) a meta-analysis making use of a robust variance estimation method. Based on their simulation results, they recommend that meta-analysts should either use the two-step method, which involves taking a weighted paper mean followed by analysis with a random-effects model, or the robust variance estimation method.

No Evidence of Creative Benefit Accompanying Dyslexia: A Meta-Analysis

2021 ◽  
pp. 002221942110103
Author(s):  
Florina Erbeli ◽  
Peng Peng ◽  
Marianne Rice
Keyword(s):  
Random Effects ◽  
Variance Estimation ◽  
Meta Analysis ◽  
Robust Variance ◽  
Summary Effect ◽  
Significant Performance ◽  
Mean And Variance ◽  
Robust Variance Estimation ◽  
The Mean ◽  
Creativity Task

Research on the question of creative benefit accompanying dyslexia has produced conflicting findings. In this meta-analysis, we determined summary effects of mean and variance differences in creativity between groups with and without dyslexia. Twenty studies were included ( n = 770 individuals with dyslexia, n = 1,671 controls). A random-effects robust variance estimation (RVE) analysis indicated no mean ( g = −0.02, p = .84) or variance differences ( g = −0.0004, p = .99) in creativity between groups. The mean summary effect was moderated by age, gender, and creativity domain. Compared with adolescents, adults with dyslexia showed an advantage over nondyslexic adults in creativity. In addition, a higher proportion of males in the dyslexia group was associated with poorer performance compared with the controls. Finally, the dyslexia group showed a significant performance disadvantage in verbal versus figural creativity. Regarding variance differences, they varied across age and creativity domains. Compared with adults, adolescents showed smaller variability in the dyslexia group. If the creativity task measured verbal versus figural or combined creativity, then the dyslexia group exhibited smaller variability. Altogether, our results suggest that individuals with dyslexia as a group are no more creative or show greater variability in creativity than peers without dyslexia.

scholarly journals Multi-level meta-analysis of single-case experimental designs using robust variance estimation

2021 ◽  
Author(s):  
Man Chen ◽  
James E Pustejovsky
Keyword(s):  
Effect Size ◽  
Variance Estimation ◽  
Single Case ◽  
Meta Analysis ◽  
Data Series ◽  
Robust Variance ◽  
Auto Correlation ◽  
Robust Variance Estimation ◽  
Multi Level ◽  
Size Estimates

Single-case experimental designs (SCEDs) are used to study the effects of interventions on the behavior of individual cases, by making comparisons between repeated measurements of an outcome under different conditions. In research areas where SCEDs are prevalent, there is a need for methods to synthesize results across multiple studies. One approach to synthesis uses a multi-level meta-analysis (MLMA) model to describe the distribution of effect sizes across studies and across cases within studies. However, MLMA relies on having accurate sampling variances of effect size estimates for each case, which may not be possible due to auto-correlation in the raw data series. One possible solution is to combine MLMA with robust variance estimation (RVE), which provides valid assessments of uncertainty even if the sampling variances of effect size estimates are inaccurate. Another possible solution is to forgo MLMA and use simpler, ordinary least squares (OLS) methods, with RVE. This study evaluates the performance of effect size estimators and methods of synthesizing SCEDs in the presence of auto-correlation, for several different effect size metrics, via a Monte Carlo simulation designed to emulate the features of real data series. Results demonstrate that the MLMA model with RVE performs properly in terms of bias, accuracy, and confidence interval coverage for estimating overall average log response ratios. The OLS estimator corrected with RVE performs the best in estimating overall average Tau effect sizes. None of the available methods perform adequately for meta-analysis of within-case standardized mean differences.

scholarly journals Zinc, Copper, and Iron in Oral Submucous Fibrosis: A Meta-Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Prageet K. Sachdev ◽  
Jeanne Freeland-Graves ◽  
S. Natasha Beretvas ◽  
Namrata Sanjeevi
Keyword(s):  
Effect Size ◽  
Variance Estimation ◽  
Meta Analysis ◽  
Oral Submucous Fibrosis ◽  
Estimation Method ◽  
Cochrane Library ◽  
Diagnosis And Prognosis ◽  
Potentially Malignant ◽  
Submucous Fibrosis ◽  
Robust Variance Estimation

Oral submucous fibrosis (OSF) is a potentially malignant disorder which causes fibrosis and inflammation of the oral mucosa. Studies have reported altered levels of trace elements in oral submucous fibrosis subjects, but findings have been inconsistent. The objective of this research is to perform a meta-analysis to summarize studies that report zinc (Zn), copper (Cu), and iron (Fe) in patients, with and without OSF. A literature search of Embase, PubMed, Cochrane Library, and Web of Science electronic databases was conducted for studies up to January 2017. A total of 34 reports met the inclusion criteria. The standardized mean difference was utilized as the effect size. The robust variance estimation method was chosen to handle dependency of multiple related outcomes in meta-analysis. There was a significant increase in the levels of Cu (effect size = 1.17, p value < 0.05, 95% confidence interval (CI): 0.164–2.171) and a significant decrease in levels of Zn (effect size = −1.95, p value < 0.05, 95% CI: −3.524 to −0.367) and Fe (effect size = −2.77, p value < 0.01, 95% CI: −4.126 to −1.406) in OSF patients. The estimation of Zn, Cu, and Fe levels may serve as additional biomarkers in the diagnosis and prognosis of OSF along with the clinical features.

Listening Ears or Reading Eyes: A Meta-Analysis of Reading and Listening Comprehension Comparisons

2021 ◽  
pp. 003465432110608
Author(s):  
Virginia Clinton-Lisell
Keyword(s):  
Listening Comprehension ◽  
Variance Estimation ◽  
Meta Analysis ◽  
Age Groups ◽  
Robust Variance ◽  
Reading Condition ◽  
P 16 ◽  
Robust Variance Estimation ◽  
Literal Comprehension

In this study, a meta-analysis of reading and listening comprehension comparisons across age groups was conducted. Based on robust variance estimation (46 studies; N = 4,687), the overall difference between reading and listening comprehension was not reliably different (g = 0.07, p = .23). Reading was beneficial over listening when the reading condition was self-paced (g = 0.13, p = .049) rather than experimenter-paced (g = −0.32, p = .16). Reading also had a benefit when inferential and general comprehension rather than literal comprehension was assessed (g = 0.36, p = .02; g = .15, p = .05; g = −0.01, p = .93, respectively). There was some indication that reading and listening were more similar in languages with transparent orthographies than opaque orthographies (g = 0.001, p = .99; g = 0.10, p = .19, respectively). The findings may be used to inform theories of comprehension about modality influences in that both lower-level skill and affordances vary comparisons of reading and listening comprehension. Moreover, the findings may guide choices of modality; however, both audio and written options are needed for accessible instruction.

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.

Systematic Review of Second Primary Oropharyngeal Cancers in Patients With p16+ Oropharyngeal Cancer

2020 ◽  
pp. 019459982095117
Author(s):  
Craig A. Bollig ◽  
David S. Lee ◽  
Angela L. Mazul ◽  
Katelyn Stepan ◽  
Sidharth V. Puram ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Random Effects ◽  
Meta Analysis ◽  
Second Primary ◽  
Random Effects Model ◽  
Treatment Information ◽  
Pooled Prevalence ◽  
Alive With Disease ◽  
Medical Librarian ◽  
Meta Analyses

Objective To systematically review the literature to determine the prevalence and clinical outcomes of second primary oropharyngeal squamous cell carcinoma (OPSCC). Data Sources Search strategies created with a medical librarian were implemented using multiple databases in October 2019. Review Methods The population of interest included adults age >18 years with a p16+ or human papillomavirus-positive OPSCC. The outcome was a synchronous or metachronous second primary OPSCC. Inclusion and exclusion criteria were designed to capture all study designs. In total, 685 records were identified by the search strategy. Two reviewers independently performed the review, extracted data, and performed a quality assessment. Primary Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. A random-effects model was used for the meta-analysis. Results A total of 2470 patients with 35 second primary OPSCCs from 15 studies were identified. The pooled prevalence of second primary OPSCC was 1.4% (range, 0%-14.3%). In the random-effects model, the prevalence was estimated at 1.3% (95% CI, 0.7%-2.3%; P = .51, I2 = 52%). Of the 30 patients with treatment information, 26 (86.7%) received surgical treatment, while 4 (13.3%) underwent nonsurgical therapy. Of the 29 patients with available survival information, 22 (75.9%) had no evidence of disease at last follow-up, 5 (17.2%) ultimately died of disease, and 2 (6.9%) were alive with disease. Conclusion Overall, the rate of second primary OPSCC in patients with an index p16+ OPSCC is low, and most patients are successfully treated. Insufficient evidence currently exists to recommend routine elective tonsillectomy during surgical treatment of p16+ OPSCC.

Bivariate Random-effects Meta-analysis of Sensitivity and Specificity with SAS PROC GLIMMIX

2010 ◽  
Vol 49 (01) ◽  
pp. 54-64 ◽  
Author(s):  
J. Menke
Keyword(s):  
Sensitivity And Specificity ◽  
Random Effects ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Meta Analysis ◽  
Empirical Evaluation ◽  
Test Accuracy ◽  
Random Effects Model ◽  
Operating Characteristics ◽  
Meta Analyses

Summary Objectives: Meta-analysis allows to summarize pooled sensitivities and specificities from several primary diagnostic test accuracy studies. Often these pooled estimates are indirectly obtained from a hierarchical summary receiver operating characteristics (HSROC) analysis. This article presents a generalized linear random-effects model with the new SAS PROC GLIMMIX that obtains the pooled estimates for sensitivity and specificity directly. Methods: Firstly, the formula of the bivariate random-effects model is presented in context with the literature. Then its implementation with the new SAS PROC GLIMMIX is empirically evaluated in comparison to the indirect HSROC approach, utilizing the published 2 x 2 count data of 50 meta-analyses. Results: According to the empirical evaluation the meta-analytic results from the bivariate GLIMMIX approach are nearly identical to the results from the indirect HSROC approach. Conclusions: A generalized linear mixed model with PROC GLIMMIX offers a straightforward method for bivariate random-effects meta-analysis of sensitivity and specificity.

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