A third variable that distorts the apparent link between exposure and outcome.
A confounder is a variable associated with both the exposure (or intervention) and the outcome under study, but which is not on the causal pathway between them, and which can therefore create a spurious or distorted estimate of effect if not controlled for. Common examples in sports-medicine research include age, training history, injury history, and baseline fitness. Good study design (randomisation, matching) or statistical adjustment (regression, stratification) are used to address confounding, though residual or unmeasured confounding can never be fully excluded in observational research.
This guide was auto-drafted and is pending editorial review.