Definition: Age-standardized rate
An age-standardized rate (ASR) is a summary measure of a rate that a population would have if it had a standard age structure. Standardization is necessary when comparing several populations that differ with respect to age because age has such a powerful influence on mortality and morbidity indicators. The most frequently used standard population are the World and the European standard populations as defined by WHO. The calculated incidence in the case of mortality is then called World Standardized incidence or mortality rate. It is normally expressed per 100 000 of population.
Eurostat, "Key data on health 2000"