Why do we measure life expectancy?
Life expectancy can be used to evaluate the overall health status of a population and identify groups who are at risk of dying early.(1) Factors such as access to medical care, physical environment characteristics, employment opportunities, social inequalities, health behaviors, and preventable health conditions can contribute to reduced life expectancy.(1,2) Life expectancy varies across population subgroups — with individuals with low incomes and certain racial/ethnic groups experiencing shorter-than-average life expectancies.(1-4)
How do we measure life expectancy?
Life expectancy is the average number of years a person can expect to live, based on the experiences of the population living in that same area.(5)
The life expectancy metric includes all deaths in a population, thus providing a snapshot of the entire community.
The data reported here have been tailored to directly address small-area estimation challenges, such as small numbers of deaths, missing age-specific death counts, and small population sizes.(6)
It can be difficult to pinpoint what causes differences in life expectancy among communities because many factors contribute to mortality.(2)
Life expectancy estimates do not change significantly from year to year. Therefore, it is not usually a sensitive measure for tracking short-term improvement.
Life expectancy estimates are calculated for census tracts by constructing a life table for each tract, then aggregating to the congressional district level. Ages are combined into five-year intervals, except the first two groups (aged 0-1 and aged 1-5 years).(6) Death rates for the age groups are calculated over the six-year period and applied to a hypothetical birth cohort to estimate the probability of surviving to the next five-year age group.(6) The life expectancy estimate is a summary measure that is based on the number and age of death of the residents in each census tract during the years of 2010-2015.(5)
This metric was calculated by aggregating estimates from smaller geographies to the congressional district level. For more information, please refer to the Congressional District Health Dashboard Technical Document.
Estimates for this metric are from U.S. Small-area Life Expectancy Estimates Project Data. The U.S. Small-Area Life Expectancy Estimates Project (USALEEP) is a joint effort of the National Association for Public Health Statistics and Information Systems (NAPHSIS), the U.S. Centers for Disease Control and Prevention’s National Center for Health Statistics (NCHS), and the Robert Wood Johnson Foundation (RWJF).
Xu J, Murphy SL, Kochanek KD, Bastian BA. Deaths: final data for 2013. National Vital Statistics Reports. 2016;64(2).
Chetty R, Stepner M, Abraham S, et al. The association between income and life expectancy in the United States, 2001-2014. Jama. 2016;315(16):1750-1766.
Kochanek KD, Murphy SL, Xu JQ, Arias E. Mortality in the United States, 2016. Hyattsville, MD: National Center for Health Statistics;2017.
Murray CJL, Kulkarni SC, Michaud C, et al. Eight Americas: Investigating Mortality Disparities across Races, Counties, and Race-Counties in the United States. PLOS Medicine. 2006;3(9):e260.
National Association for Public Health Statistics and Information Systems. USALEEP Neighborhood Life Expectancy Project Message Guide. 2018; http://usaleep.nptoolkit.org/wp-content/uploads/sites/19/2018/05/USALEEP-Message-Guide_Final.pdf. Accessed September 27, 2018.
Arias E, Escobedo LA, Kennedy J, Fu C, Cisewski J. U.S. Small-area Life Expectancy Estimates Project: Methodology and Results Summary. 2018.
Last updated: January 24, 2023