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Research Synthesis Methods

Adam R Hafdahl
This ninth 'Article Alert' installment's print component presents 200 methodological articles about research synthesis published in 2014, all grouped by type of contribution and assigned descriptive keywords. More than 5300 articles, book chapters, and other types of work from 2004-2008 and 2014 have been added to the archive component since the eighth installment. The online Supporting Information provides this and all previous installments' print- and archive-component records, most with a DOI name or other online identifier...
September 9, 2018: Research Synthesis Methods
Mike W-L Cheung
Meta-analysis and structural equation modeling (SEM) are two of the most prominent statistical techniques employed in the behavioral, medical, and social sciences. They each have their own well-established research communities, terminologies, statistical models, software packages, and journals (Research Synthesis Methods and Structural Equation Modeling: A Multidisciplinary Journal). In this paper, I will provide some personal reflections on combining meta-analysis and SEM in the forms of meta-analytic SEM (MASEM) and SEM-based meta-analysis...
September 3, 2018: Research Synthesis Methods
Suzy Paisley, Margaret J Foster
No abstract text is available yet for this article.
September 3, 2018: Research Synthesis Methods
Dylan Kneale, James Thomas, Alison O'Mara-Eves, Richard Wiggins
This paper critically explores how survey and routinely collected data could aid in assessing the generalisability of public health evidence. We propose developing approaches that could be employed in understanding the relevance of public health evidence, and investigate ways of producing meta-analytic estimates tailored to reflect local circumstances, based on analyses of secondary data. Currently, public health decision-makers face challenges in interpreting 'global' review evidence to assess its meaning in local contexts...
August 21, 2018: Research Synthesis Methods
Patricia F Anderson, Carol Shannon, Skye Bickett, Joanne Doucette, Pamela Herring, Andrea Kepsel, Tierney Lyons, Scott McLachlan, Lin Wu
When the Medical Library Association identified questions critical for the future of the profession, it assigned groups to use systematic reviews to find the answers to these questions. Group 6, whose question was on emerging technologies, recognized early on that the systematic review process would not work well for this question, which looks forward to predict future trends, whereas the systematic review process looks back in time. We searched for new methodologies that were more appropriate to our question, developing a process that combined systematic review, text mining, and visualization techniques...
August 21, 2018: Research Synthesis Methods
Areti Angeliki Veroniki, Dan Jackson, Ralf Bender, Oliver Kuss, Dean Langan, Julian P T Higgins, Guido Knapp, Georgia Salanti
Meta-analyses are an important tool within systematic reviews to estimate the overall effect size and its confidence interval for an outcome of interest. If heterogeneity between the results of the relevant studies is anticipated, then a random-effects model is often preferred for analysis. In this model, a prediction interval for the true effect in a new study also provides additional useful information. However, the DerSimonian and Laird method - frequently used as the default method for meta-analyses with random effects - has been long challenged due to its unfavourable statistical properties...
August 21, 2018: Research Synthesis Methods
Alexis Langlois, Jian-Yun Nie, James Thomas, Quan Nha Hong, Pierre Pluye
OBJECTIVE: Identify the most performant automated text classification method (eg, algorithm) for differentiating empirical studies from nonempirical works in order to facilitate systematic mixed studies reviews. METHODS: The algorithms were trained and validated with 8050 database records, which had previously been manually categorized as empirical or nonempirical. A Boolean mixed filter developed for filtering MEDLINE records (title, abstract, keywords, and full texts) was used as a baseline...
August 13, 2018: Research Synthesis Methods
Dean Langan, Julian P T Higgins, Dan Jackson, Jack Bowden, Areti Angeliki Veroniki, Evangelos Kontopantelis, Wolfgang Viechtbauer, Mark Simmonds
Studies combined in a meta-analysis often have differences in their design and conduct that can lead to heterogeneous results. A random-effects model accounts for these differences in the underlying study effects, which includes a heterogeneity variance parameter. The DerSimonian-Laird method is often used to estimate the heterogeneity variance, but simulation studies have found the method can be biased and other methods are available. This paper compares the properties of nine different heterogeneity variance estimators using simulated meta-analysis data...
August 1, 2018: Research Synthesis Methods
Amanda Wanner, Niki Baumann
BACKGROUND: Both PubMed and Ovid MEDLINE contain records from the MEDLINE database. However, there are subtle differences in content, functionality, and search syntax between the two. There are many instances in which researchers may wish to search both interfaces, such as when conducting supplementary searching for a systematic review to retrieve unique content from PubMed or when using a previously published search strategy from a different interface, but little guidance on how to best conduct these searches...
August 1, 2018: Research Synthesis Methods
Chris Cooper, Sarah Dawson, Jaime Peters, Jo Varley-Campbell, Emma Cockcroft, Jess Hendon, Rachel Churchill
In this method note, we question if the primary search strategy in a systematic review should be accompanied by a search narrative. A search narrative could offer a conceptual and contextual report on the search strategy, which we suggest might benefit the peer review of literature searches and increase engagement with, and discussion of, the literature search strategy from review stakeholders, topic experts, and lay users of research. Search narratives would also increase the transparency of decision-making in literature searching...
July 21, 2018: Research Synthesis Methods
Yuan Zhang, Elie A Akl, Holger J Schünemann
Systematic reviews are essential to produce trustworthy guidelines. To assess the certainty of a body of evidence included in a systematic review the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group has developed an approach that is currently used by over 100 organisations, including the World Health Organization and the Cochrane Collaboration. GRADE provides operational definitions and instructions to rate the certainty of the evidence for each outcome in a review as high, moderate, low, or very low for the effects of interventions, prognostic estimates, values and preferences, test accuracy and resource utilization...
July 14, 2018: Research Synthesis Methods
María Rubio-Aparicio, José Antonio López-López, Julio Sánchez-Meca, Fulgencio Marín-Martínez, Wolfgang Viechtbauer, Wim Van den Noortgate
The random-effects model, applied in most meta-analyses nowadays, typically assumes normality of the distribution of the effect parameters. The purpose of this study was to examine the performance of various random-effects methods (standard method, Hartung's method, profile likelihood method, and bootstrapping) for computing an average effect size estimate and a confidence interval (CI) around it, when the normality assumption is not met. For comparison purposes, we also included the fixed-effect model. We manipulated a wide range of conditions, including conditions with some degree of departure from the normality assumption, using Monte Carlo simulation...
July 10, 2018: Research Synthesis Methods
José A López-López, Matthew J Page, Mark W Lipsey, Julian P T Higgins
Systematic reviews often encounter primary studies that report multiple effect sizes based on data from the same participants. These have the potential to introduce statistical dependency into the meta-analytic data set. In this paper, we provide a tutorial on dealing with effect size multiplicity within studies in the context of meta-analyses of intervention and association studies, recommending a three-step approach. The first step is to define the research question and consider the extent to which it mainly reflects interest in mean effect sizes (which we term a convergent approach) or an interest in exploring heterogeneity (which we term a divergent approach)...
July 3, 2018: Research Synthesis Methods
Piotr Przybyła, Austin J Brockmeier, Georgios Kontonatsios, Marie-Annick Le Pogam, John McNaught, Erik von Elm, Kay Nolan, Sophia Ananiadou
Screening references is a time-consuming step necessary for systematic reviews and guideline development. Previous studies have shown that human effort can be reduced by using machine learning software to prioritise large reference collections such that most of the relevant references are identified before screening is completed. We describe and evaluate RobotAnalyst, a Web-based software system that combines text-mining and machine learning algorithms for organising references by their content and actively prioritising them based on a relevancy classification model trained and updated throughout the process...
June 28, 2018: Research Synthesis Methods
Joy Leahy, Aisling O'Leary, Nezam Afdhal, Emma Gray, Scott Milligan, Malte H Wehmeyer, Cathal Walsh
The use of individual patient data (IPD) in network meta-analysis (NMA) is becoming increasingly popular. However, as most studies do not report IPD, most NMAs are performed using aggregate data for at least some, if not all, of the studies. We investigate the benefits of including varying proportions of IPD studies in an NMA. Several models have previously been developed for including both aggregate data and IPD in the same NMA. We performed a simulation study based on these models to examine the impact of additional IPD studies on the accuracy and precision of the estimates of both the treatment effect and the covariate effect...
June 20, 2018: Research Synthesis Methods
Adam R Hafdahl
This eighth installment of 'Article Alerts' includes a print component with 200 methodological articles about research synthesis published in 2013. Since the preceding installment, more than 3400 articles, dissertations, book chapters, and other types of work in this methodological domain have been added to the archive component, all from 2009 to 2013. The online Supporting Information now includes over half of the parent compilation's more than 26 000 records: 1000 from the print component and more than 13 000 from the archive component...
June 2018: Research Synthesis Methods
Nazila Alinaghi, W Robert Reed
This paper studies the performance of the FAT-PET-PEESE (FPP) procedure, a commonly employed approach for addressing publication bias in the economics and business meta-analysis literature. The FPP procedure is generally used for 3 purposes: (1) to test whether a sample of estimates suffers from publication bias, (2) to test whether the estimates indicate that the effect of interest is statistically different from zero, and (3) to obtain an estimate of the mean true effect. Our findings indicate that the FPP procedure performs well in the basic but unrealistic environment of fixed effects, where all estimates are assumed to derive from a single population value and sampling error is the only reason for why studies produce different estimates...
June 2018: Research Synthesis Methods
O O Babatunde, V Tan, J L Jordan, K Dziedzic, C A Chew-Graham, C Jinks, J Protheroe, D A van der Windt
BACKGROUND & AIMS: Barriers to dissemination and engagement with evidence pose a threat to implementing evidence-based medicine. Understanding, retention, and recall can be enhanced by visual presentation of information. The aim of this exploratory research was to develop and evaluate the accessibility and acceptability of visual summaries for presenting evidence syntheses with multiple exposures or outcomes to professional and lay audiences. METHODS: "Evidence flowers" were developed as a visual method of presenting data from 4 case scenarios: 2 complex evidence syntheses with multiple outcomes, Cochrane reviews, and clinical guidelines...
June 2018: Research Synthesis Methods
Lifeng Lin, Haitao Chu
In medical sciences, a disease condition is typically associated with multiple risk and protective factors. Although many studies report results of multiple factors, nearly all meta-analyses separately synthesize the association between each factor and the disease condition of interest. The collected studies usually report different subsets of factors, and the results from separate analyses on multiple factors may not be comparable because each analysis may use different subpopulation. This may impact on selecting most important factors to design a multifactor intervention program...
June 2018: Research Synthesis Methods
Sarah Donegan, Sofia Dias, Catrin Tudur-Smith, Valeria Marinho, Nicky J Welton
BACKGROUND: Meta-regression results must be interpreted taking into account the range of covariate values of the contributing studies. Results based on interpolation or extrapolation may be unreliable. In network meta-regression (NMR) models, which include covariates in network meta-analyses, results are estimated using direct and indirect evidence; therefore, it may be unclear which studies and covariate values contribute to which result. We propose graphs to help understand which trials and covariate values contribute to each NMR result and to highlight extrapolation or interpolation...
June 2018: Research Synthesis Methods
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