Life expectancy what does it mean

Share life expectancy Post the Definition of life expectancy to Facebook Share the Definition of life expectancy on Twitter. Time Traveler for life expectancy The first known use of life expectancy was in See more words from the same year. Style: MLA. English Language Learners Definition of life expectancy. Medical Definition of life expectancy. Legal Definition of life expectancy. More from Merriam-Webster on life expectancy Britannica. Get Word of the Day daily email! Test Your Vocabulary.

Test your visual vocabulary with our question challenge! Love words? This means that the group of year-old children alive around the world in could expect to live another Finally, another point to bear in mind is that period and cohort life expectancy estimates are statistical measures, and they do not take into account any person-specific factors such as lifestyle choices.

Clearly, the length of life for an average person is not very informative about the predicted length of life for a person living a particularly unhealthy lifestyle. In practical terms, estimating life expectancy entails predicting the probability of surviving successive years of life, based on observed age-specific mortality rates.

How is this actually done? Age-specific mortality rates are usually estimated by counting or projecting the number of age-specific deaths in a time interval e.

To ensure that the resulting estimates of the probabilities of death within each age interval are smooth across the lifetime, it is common to use mathematical formulas, to model how the force of mortality changes within and across age intervals.

For some countries and for some time intervals, it is only possible to reconstruct life tables from either period or cohort mortality data. As a consequence, in some instances—for example in obtaining historical estimates of life expectancy across world regions —it is necessary to combine period and cohort data.

Life tables are not just instrumental to the production of life expectancy figures as noted above , they also provide many other perspectives on the mortality of a population. This chart provides an example, plotting survival curves for individuals born at different points in time, using cohort life tables from England and Wales. At any age level in the horizontal axis, the curves in this visualization mark the estimated proportion of individuals who are expected to survive that age.

As we can see, less than half of the people born in in England and Wales made it past their 50th birthday. Since life expectancy estimates only describe averages, these indicators are complementary, and help us understand how health is distributed across time and space. In our entry on Life Expectancy you can read more about related complementary indicators, such as the median age of a population.

In practice, however, things are often more complicated: One important distinction and clarification is the difference between cohort and period life expectancy. An example to illustrate the measurement of life expectancy. Using data from the Centers for Disease Control and Prevention CDC , the report states the average life expectancy of a child born in dropped to Life expectancy is a projection estimating what the average age of death will be for people born today.

It is based on data regarding the health of the nation as well as estimates of the impact of current trends decades in the future. The latest data for these two measures supports the conclusion that US health is decreasing.

Average age of death: This is based on the ages of everyone who died in a given year. The US death rate ranged between In , the average age of death fell to Death rates: This is calculated based on the proportion of people who died in a given year.

A version of the death rate is the age-adjusted death rate, which accounts for population variations in different geographic areas. In , the age-adjusted death rate was Life expectancy: This calculation uses age-specific death rates. Life expectancy estimates how long a person is expected to live based on current data. It does not measure the average age at which a person dies in a given year. While the 0. Increases in death rates among younger people can lead to a decrease in life expectancy.

CDC data shows how this has changed. Opioid addiction, deaths, and treatment: The latest analysis of the data. For to year-olds, the overdose death rate increased from Life expectancy figures are based on a series of other data points—specifically death rates—that could be investigated further based on age, geography, cause of death and a number of other variables.