Evidence quality
Bias
A systematic error that can push study results away from the truth.
What it means
Definition
Bias. Bias is not simply personal opinion. In research, it means a design, measurement, analysis or publication problem that systematically distorts the result.
What it can tell you
It can help clarify what sort of evidence or claim is being discussed.
What it cannot tell you
It cannot, by itself, prove that the headline is accurate or clinically important.
Headline trap
Why this matters in headlines
A headline based on biased evidence may be confident even when the underlying estimate is unreliable.