Tables
- Table 1
Main sources of bias in clinical studies
Type of bias Description Selection bias Missing or inadequate randomisation: participant characteristics, including potential confounders, may differ between the experimental arms. Performance bias Missing or inadequate blinding of outcome assessor: a physician may be induced to detect improvements in treated individuals. Detection bias Missing or inadequate blinding of participants: an individual may be induced to perceive health improvements if they know they are being treated. Attrition bias Too many withdrawals, or unbalanced dropout rates among the arms: loss in statistical power, misleading outcome interpretation. Reporting bias Selective outcome reporting: in general, authors may be induced to select the findings to report (for example, due to presence of a funding institution).