Statistics and risk
Subgroup analysis
An analysis testing whether results differ within a smaller defined group.
What it means
Definition
Subgroup analysis. Subgroup analyses can be useful, but they are often underpowered and prone to false positives. They are strongest when pre-specified, biologically plausible and replicated.
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 treatment may appear to work only in one subgroup by chance if many subgroups were explored.