Bias > Reporting Bias
What is Reporting Bias?
Reporting bias (also called selective reporting) affects which studies “come to light” and which do not. Studies might be selected (or not selected) for a myriad of reasons including personal agendas, lack of knowledge, or sloppy analysis methods. This type of bias is a substantial problem in scientific reporting and clinical trial reporting.
Reporting bias means that only a selection of results are included in any analysis, which typically covers only a fraction of relevant evidence. This can lead to inappropriate decisions (for example, prescribing ineffective or harmful drugs), resource waste and misguided future research.
The umbrella term “reporting bias” covers a wide range of different biases, all of which affect which publications are more likely to be seen than others.
Types of Reporting Bias
- Citation bias: basing your analysis on studies that you find in the citations of other studies.
- Language bias: ignoring studies not published in your native Language.
- Location bias: certain reports or studies are harder to find than others. For example, studies that are published in journals might be indexed higher in databases.
- Duplicate publication bias: studies that are published in more than one place might get more weighting than other studies.
- Outcome reporting bias: selective reporting of certain outcomes, such as outcomes that paint a company in a good light.
- Publication bias: studies with positive findings are more likely to be published — and published faster — than studies with negative findings or no significant findings.
- Time lag bias: some studies take years to be published, especially if they show no effect or have unwanted results. Studies that are positive or newsworthy are published much faster.
Blumle A, Antes G, Schumacher M, Just H, Von Elm E: Clinical research projects at a German medical faculty: follow-up from ethical approval to publication and citation by others. J Med Ethics. 2008, 34: e20-10.1136/jme.2008.024521.
Sterne JAC, Egger M, Moher D. (Editors) (2008). Chapter 10: Addressing reporting biases in Cochrane Handbook for Systematic Reviews of Interventions. Version 5.0.1 [updated March 2011]. The Cochrane Collaboration.