the likelihood that a study, review, or analysis contains systematic errors or deviations from the truth that may distort its results or conclusions. A high risk of bias can lead to invalid, unreliable, or misleading findings, whereas a low risk of bias increases confidence in the results.
Abbreviation: RoB
Example
A systematic review of clinical trials for a new diabetes medication includes a Risk of Bias Assessment. Each trial is rated for factors such as randomization, blinding, completeness of outcome data, and selective reporting. One study is judged to have a high RoB because participants and investigators were not blinded, which could have influenced the reported outcomes, while other studies are rated as low RoB due to strong methodological safeguards.