Evidence-appraisal glossary
Generalizability
Generalizability is how well conclusions drawn from a study sample extend to the broader population it is meant to represent. It depends on who was sampled and how, so a result from a narrow or unrepresentative sample may not describe the wider group accurately.
Also called: generalisability, generalization, representativeness.
Generalizability describes the reach of a study's conclusions from its sample to a larger target population. It is closely related to external validity and often used interchangeably, though generalizability emphasizes the link between the sample and the population it was drawn from, driven by sampling and recruitment. A finding generalizes well when the sample resembles the target population on characteristics that could change the result. When reading a study, identify the stated target population, examine how participants were selected, and note who was excluded or declined to enroll, since volunteers and referral-center patients often differ from the general public. Then ask whether those differences plausibly affect the outcome. Example: a survey of health behaviors recruited only through a single university's students cannot be assumed to describe a whole country's adults, because age, education, and access differ systematically, and those differences bear directly on the behaviors being measured.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.