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Research Synthesis Methods

C Spry, M Mierzwinski-Urban
OBJECTIVE: The objective of this study was to investigate the impact of the peer review of literature search strategies prepared in support of rapid reviews. METHODS: A sample of 200 CADTH rapid reviews was selected. For each rapid review meeting the inclusion criteria, the pre-peer reviewed and corresponding post-peer reviewed search strategies were run and the search results were compared. Bibliographic records retrieved solely by the post-peer reviewed search strategy and included in the rapid review report were identified as representing "included studies"...
November 8, 2018: Research Synthesis Methods
H Thom, I R White, N J Welton, G Lu
Network meta-analysis compares multiple treatments from studies that form a connected network of evidence. However, for complex networks it is not easy to see if the network is connected. We use simple techniques from graph theory to test the connectedness of evidence networks in network meta-analysis. The method is to build the adjacency matrix for a network, with rows and columns corresponding to the treatments in the network and entries being one or zero depending on whether the treatments have been compared or not, and with zeros along the diagonal...
November 7, 2018: Research Synthesis Methods
Sarah Donegan, Sofia Dias, Nicky J Welton
When numerous treatments exist for a disease (treatments 1, 2, 3 etc.), network meta-regression (NMR) examines whether each relative treatment effect (e.g. mean difference for 2 vs. 1, 3 vs. 1, 3 vs. 2 etc.) differs according to a covariate (e.g. disease severity). Two consistency assumptions underlie NMR: consistency of the treatment effects at the covariate value zero and consistency of the regression coefficients for the treatment by covariate interaction. The NMR results may be unreliable when the assumptions do not hold...
October 26, 2018: Research Synthesis Methods
Isabelle Albert, David Makowski
The mixed treatment comparison (MTC) method has been proposed to combine results across trials comparing several treatments. MTC allows coherent judgments on which of the treatments is the most effective. It produces estimates of the relative effects of each treatment compared with every other treatment by pooling direct and indirect evidence. In this article, we explore how this methodological framework can be used to rank a large number of agricultural crop species from yield data collected in field experiments...
October 24, 2018: Research Synthesis Methods
Jens Jap, Ian J Saldanha, Bryant T Smith, Joseph Lau, Christopher H Schmid, Tianjing Li
INTRODUCTION: During systematic reviews, data abstraction is labor- and time-intensive and error-prone. Existing data abstraction systems do not track specific locations and contexts of abstracted information. To address this limitation, we developed a software application, the Data Abstraction Assistant (DAA), and surveyed early users about their experience using DAA. FEATURES OF DAA: We designed DAA to encompass three essential features: (1) a platform for indicating the source of abstracted information; (2) compatibility with a variety of data abstraction systems; and (3) user-friendliness...
October 16, 2018: Research Synthesis Methods
Suzy Paisley, Margaret J Foster
No abstract text is available yet for this article.
October 16, 2018: Research Synthesis Methods
Andrew Booth
No abstract text is available yet for this article.
September 24, 2018: 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 2 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 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
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...
September 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...
September 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...
September 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...
September 2018: Research Synthesis Methods
Evangelos Kontopantelis
BACKGROUND: Individual patient data (IPD) meta-analysis allows for the exploration of heterogeneity and can identify subgroups that most benefit from an intervention (or exposure), much more successfully than meta-analysis of aggregate data. One-stage or two-stage IPD meta-analysis is possible, with the former using mixed-effects regression models and the latter obtaining study estimates through simpler regression models before aggregating using standard meta-analysis methodology. However, a comprehensive comparison of the two methods, in practice, is lacking...
September 2018: Research Synthesis Methods
Yu-Xuan Su, Yu-Kang Tu
Network meta-analysis compares multiple treatments in terms of their efficacy and harm by including evidence from randomized controlled trials. Most clinical trials use parallel design, where patients are randomly allocated to different treatments and receive only 1 treatment. However, some trials use within person designs such as split-body, split-mouth, and crossover designs, where each patient may receive more than one treatment. Data from treatment arms within these trials are no longer independent, so the correlations between dependent arms need to be accounted for within the statistical analyses...
September 2018: Research Synthesis Methods
Juan Víctor Ariel Franco, Virginia Laura Garrote, Camila Micaela Escobar Liquitay, Valeria Vietto
OBJECTIVE: Search strategies are essential for the adequate retrieval of studies in a systematic review (SR). Our objective was to identify problems in the design and reporting of search strategies in a sample of new Cochrane SRs first published in The Cochrane Library in 2015. STUDY DESIGN AND SETTING: We took a random sample of 70 new Cochrane SRs of interventions published in 2015. We evaluated their design and reporting of search strategies using the recommendations from the Cochrane Handbook for Systematic Reviews of Interventions, the Methodological Expectations of Cochrane Intervention Reviews, and the Peer Review of Electronic Search Strategies evidence-based guideline...
September 2018: Research Synthesis Methods
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