Tag Archives: Publication bias

Recommended: Search for unpublished data by systematic reviewers: an audit

The authors looked at all systematic reviews (excluding methodological reviews) published in a few key journals as well as a random sample of Cochrane reviews to see how often the authors tried to search for unpublised data. The answer is not often enough (64% or 130/203). The article also describes the success rate in getting unpublished data when the attempt was made (89% or 116/130) and how often authors found evidence of publication bias when they did such an assessment (40% or 27/68). Although some people have argued that it is not that important to search for unpublised data, this is still a big concern. A closely related article is Searching for unpublished data for Cochrane reviews: cross sectional study. Continue reading

Recommended: Differences between information in registries and articles did not influence publication acceptance

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Here’s a research article tackling the same problem of changing outcome measures after the data is collected. Apparently, this occurs in 66 of the 226 papers reviewed here or almost 30% of the time. The interesting thing is that whether this occurred or not was independent of whether paper was accepted. So journal editors are missing an opportunity here to improve the quality of the published literature by demanding that researchers abide by the choices that they made during trial registration. Continue reading

Recommended: The COMPare Project

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One of the many problems with medical publications is that researchers will choose which outcomes to report based on their statistical significance rather than their clinical importance. This can seriously bias your results. You can easily avoid this potential bias by specifying your primary and secondary outcome measures prior to data collection. Apparently, though, some researchers will change their minds after designating these outcome variables and fail to report on some of the outcomes and/or add new outcomes that were not specified prior to data analysis. How often does this occur? A group of scientists at the Centre for Evidence-Based Medicine at the University of Oxford are trying to find out. Continue reading

Recommended: Restoring invisible and abandoned trials

Too much research data goes unreported, leading to a serious distortion of the evidence base that clinicians need to make intelligent medical decisions. The authors of this paper in BMJ argue that if you can document that a study has been abandoned before publication, and if you formally requestthe researchers to publish the data, and if they fail to act within a certain amount of time,then the data should be considered public access so that you or anyone else could publish those results. It’s an interesting proposal and one that will generate a lot of controversy. Continue reading