|Data Dictionary:||ACS 2011 (1-Year Estimates)|
|Data Source:||U.S. Census Bureau|
Universe: Universe: American Indian and Alaska Native alone population 15 to 54 years
|ACS 2011-1yr Summary File: Technical Documentation -> Appendix A. Supplemental Documentation -> Subject Definitions -> Population Variables -> Age -> Median Age|
The median age is the age that divides the population into two equal-size groups. Half of the population is older than the median age and half is younger. Median age is based on a standard distribution of the population by single years of age and is shown to the nearest tenth of a year. (See the sections on "Standard Distributions" and "Medians" under "Derived Measures.")
|ACS 2011-1yr Summary File: Technical Documentation -> Appendix A. Supplemental Documentation -> Subject Definitions -> Population Variables -> Marital Status/Marital History -> Median Age at First Marriage|
The median age at first marriage is calculated indirectly by estimating the proportion of young people who will marry during their lifetime, calculating one-half of this proportion, and determining the age (at the time of the survey) of people at this half-way mark by osculatory interpolation. It does not represent the actual median age of the population who married during the calendar year. It is shown to the nearest tenth of a year. Henry S. Shryock and Jacob S. Siegel outline the osculatory procedure in Methods and Materials of Demography, First Edition (May 1973), Volume 1, pages 291-296.