Statistics and risk
Statistical power
The ability of a study to detect an effect of a specified size if it truly exists.
What it means
Definition
Statistical power. Statistical power depends on sample size, effect size, event rate and variability. Underpowered studies can miss real effects or produce exaggerated positive estimates when results happen to be significant.
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 negative small trial may be inconclusive rather than proof that an intervention does not work.