Statistical Significance Versus Clinical Significance: Why the Difference Matters

Two Separate Questions, Easily Conflated

"Is this result statistically real?" and "Does this result actually matter to a patient's life?" are two entirely separate questions — a treatment can comfortably answer yes to the first while still answering no to the second.

The Minimal Clinically Important Difference

To address this gap, rehabilitation researchers commonly use the concept of the minimal clinically important difference (MCID) — the smallest change in an outcome measure, such as a pain or function score, that a patient would actually recognise as a meaningful improvement in their own life, as opposed to a statistical artefact detectable only through group-level analysis (Page, 2014).

Why This Distinction Changes How Research Should Be Read

A trial can report a statistically significant improvement in pain scores that falls well below the established MCID for that condition — technically a real effect, but one unlikely to be noticed or valued by the person experiencing it. A critical reader of clinical research needs to ask not just "was this significant?" but "was this large enough to matter?"