Evidence-appraisal glossary
Age standardization
Age standardization adjusts disease or death rates so that populations with different age structures can be compared fairly, by referring both to one common standard age distribution rather than to their own. It removes the distortion that arises because age itself strongly affects most health outcomes.
Also called: standardization, age adjustment, direct standardization.
Because an older population will show more disease from age alone, comparing crude rates between populations can mislead; age standardization holds the age mix constant so any remaining difference reflects something other than age. The direct method applies each population's observed age-specific rates to a standard population, while the indirect method applies standard rates to each population and compares observed to expected events. A standardized rate is not a real rate that anyone experiences; it is a summary whose value depends on the chosen standard population, so two studies using different standards cannot be compared directly.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.