“BIAS” Detectives 101: Top 3 Things You Need to Know .

Bias threatens the credibility of randomized trials by pushing results away from the truth in a predictable direction, unlike chance, which creates random variation around the true effect. Key risks arise when allocation is poorly randomized or concealed, when blinding of patients, providers, or assessors is absent, when outcomes are missing, or when selective reporting occurs. These flaws undermine confidence in treatment effects and can mislead clinical decisions. Careful appraisal of these domains—supported by structured risk-of-bias tools—helps determine whether study findings are trustworthy enough to inform practice.