Medianalter

Medianalter, or median age, is a demographic statistic that describes the age distribution of a population. It is the age at which half of the people are younger and half are older. Unlike the mean age, which sums all ages and divides by the number of individuals, the median is less affected by very young or very old outliers and provides a robust central point of the age structure.

Calculation is based on the ordered ages of the population. The median is the age at which 50 percent of people are younger and 50 percent are older. With grouped data, the median can be estimated by interpolating within the age interval that contains the 50th percentile. For example, in a population of five people with ages 22, 28, 34, 39 and 46, the median age is 34.

The median age is a key indicator of population aging and is widely used in policy analysis and cross-national comparisons. A higher median age typically signals an aging population and has implications for pension systems, healthcare demand, education, and the labor market. It helps describe long-term demographic trends and planning needs.

Factors influencing the median age include fertility rates, life expectancy, and migration. The metric can change slowly as cohorts age and new birth cohorts enter the population. Limitations include sensitivity to the age structure and data quality, and its lack of information about age distribution details beyond the central point. Related concepts include the mean age and measures of age structure.