What is evidence? Things to keep in mind:
Who pays for science?
Most scientific research is funded by government, companies doing research and development, and non-profit entities. Because science is attempting to get at some "truth," the source of research funding shouldn't have a significant effect on the outcome of scientific research, right?
» Read Industry sponsorship and research outcome Cochrane Database Syst Rev. 2012 Dec 12;12:MR000033).
» Read Food Politics, a blog by Marion Nestle that often addresses the issues of industry sponsored research
Peer review refers to a process whereby scholarly work (ie, an article) is reviewed and critiqued by experts to ensure it meets some standards of acceptance before it is published.
Does this process make for better science?
» Read Editorial peer review for improving the quality of reports of biomedical studies (Cochrane Database Syst Rev. 2007 Apr 18;(2):MR000016)
What gets published? ("Publication bias")
Studies that report interventions that had no effect are less likely to get published. What does this mean in terms of the state of knowledge on a topic?
» Read Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias (PLoS One. 2008 Aug 28;3(8):e3081)
Oops! I made a mistake (or ... was it cheating..?)
Occasionally, researchers make mistakes, and sometimes those mistakes affect the conclusions of a published article. Articles may be retracted if the mistake is significant. This is a formal process where the author or journal publishes a statement outlining the error. Sometimes, however, retraction is the result of fraud, plagiarism, or other bad acts.
» Read Retraction Watch.
Opinion or fact?
Do the conclusions of the article follow the evidence that's presented? Are opinions or notions posited as facts?
» Search "As is well known..." in Google Scholar.
» Read A Propaganda Index for Reviewing Problem Framing in Articles and Manuscripts: An Exploratory Study (PLoS One. 2011;6(5):e19516)
CV boosting: Does this study add to the body of knowledge, or is it just something the author is doing to add to his/her list of publications?
(In)significance of a single study: Science is incremental. Beware of any study that's proclaimed to be a "breakthrough."
» Read Evidence-based public health (RC Brownson. New York; Oxford: Oxford University Press, 2011)
What's the question?
» Compare: "Our intervention worked toward fixing Problem X" vs. "The best intervention(s) for fixing Problem X is/are:..."
What to consider when looking at survey or estimated data:Adopted from the UCSF Family Health Outcomes Project
Reliability and validity
Adopted from Chapter 3, Conducting research literature reviews: from the Internet to paper, by Arlene Fink.
Reliable data collection is relatively free from "measurement error"
» Is the survey written at a reading level too high for the people completing it?
» Is the device used to measure elapsed time in an experiment accurate?
Validity refers to how well a measure assesses what it claims to measure
» If the survey is supposed to measure "quality of life," how is that concept defined?
» How accurately can this animal study of drug metabolism be extrapolated to humans?