Evidence-appraisal glossary
Reporting bias
Reporting bias is the distortion of the evidence base that occurs when whether and how results are shared depends on their direction or statistical significance rather than their scientific merit. It is an umbrella term whose forms include publication bias, when whole studies go unpublished, and selective outcome reporting, when specific results within a study are dropped or downplayed.
Also called: selective reporting, selective reporting bias.
Reporting bias skews the published record because favorable or statistically significant findings tend to be written up, and given prominence, more readily than disappointing or null ones, even when the underlying studies were sound. Publication bias and selective outcome reporting are two of its main forms, acting at the level of whole studies and of individual outcomes within a study. Comparing a published report against its pre-registered protocol is a standard way to catch outcome-level reporting bias.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.