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What does life expectancy mean?
Life expectancy is an estimate of the average number of additional years that a person of a given age can expect to live. The most common measure is life expectancy at birth. It is a hypothetical measure that assumes the age-specific death rates for the year in question will apply throughout the lifetime of individuals born in that year. Life expectancy is commonly given for specific categories, rather than for the population in general, because the measure differs considerably by sex, age, race, and geographic location. Life expectancy reflects local conditions. In less-developed countries, life expectancy at birth is relatively low, compared with more-developed countries.
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How is life expectancy measured?
Life expectancy is an estimate of the average number of additional years that a person of a given age can expect to live. The most common measurement is life expectancy at birth.
Life expectancy is calculated using a life table. This table uses data from age-specific death rates for a population. The data is derived from national census and vital statistics data. From this, the average life expectancy is calculated for each age group within the population.
It is a hypothetical measure that assumes the age-specific death rates for the year in question will apply throughout the lifetime of individuals born in that year. Life expectancy differs considerably by sex, age, race, and geographic location.
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Why might life expectancy differ between countries?
Life expectancy, the average number of years a person is expected to live, differs across countries due to various factors. In less-developed countries, life expectancy at birth is relatively low compared to more-developed ones, potentially due to high infant mortality rates from infectious diseases or lack of clean water.
Variations can also stem from differences in the kinds of diseases, their rates of occurrence, and the age groups affected. For example, infant mortality rates in Africa are about six times higher than in Europe. Additionally, factors such as sanitation, nutrition, and access to modern health care play a significant role.
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What factors can affect a person's life expectancy?
Several factors can influence a person's life expectancy, including genetics, sex, and geographic location. Lifestyle choices such as diet, physical activity, and avoiding smoking and excessive alcohol consumption also play a significant role. Access to healthcare, including preventive measures like vaccinations and screenings, and living in an environment with low pollution levels, can further impact how long a person is expected to live.
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How have advances in medicine changed life expectancy over time?
Medical advancements have significantly increased life expectancy. In 1901 in the United Kingdom, the average life expectancy at birth was 48 years for males and 51.6 years for females. By the 1980s, it had risen to 71.4 years for males and 77.2 years for females. Similar increases occurred in other industrialized countries.
Factors driving this change include combating infection, advancements in endocrinology, nutrition, cell biology insights, and progress in biochemistry and physiology. Also important are biomedical engineering innovations like ultrasound, CAT scans, and NMR. These developments have shifted the focus from simply keeping people alive to maintaining their fitness.
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Why do some groups of people have higher or lower life expectancy rates?
Life expectancy, the average number of years a person is expected to live, varies across different groups due to factors like sex, race, and geographic location. In less-developed countries, life expectancy is lower compared to more-developed ones, often due to high infant mortality rates from infectious diseases or lack of clean water.
Genetic factors also play a role in longevity, with studies showing that variations in genes can influence susceptibility to diseases like cancer and heart disease. Additionally, lifestyle choices such as diet and exercise impact the aging process; plant-based diets are associated with longer life spans. Infant mortality rates, which differ by country, are affected by sanitation, nutrition, and access to health care.
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life expectancy, estimate of the average number of additional years that a person of a given age can expect to live. The most common measure of life expectancy is life expectancy at birth. Life expectancy is a hypothetical measure. It assumes that the age-specific death rates for the year in question will apply throughout the lifetime of individuals born in that year. The estimate, in effect, projects the age-specific mortality (death) rates for a given period over the entire lifetime of the population born (or alive) during that time. The measure differs considerably by sex, age, race, and geographic location. Therefore, life expectancy is commonly given for specific categories, rather than for the population in general. For example, the life expectancy for white females in the United States who were born in 2021 is 79.2 years, while a Black male born in the same year is 66.7 years..
Life expectancy reflects local conditions. In less-developed countries, life expectancy at birth is relatively low, compared with more-developed countries. In some less-developed countries, life expectancy at birth may be lower than life expectancy at age 1, because of high infant mortality rates (commonly due to infectious disease or lack of access to a clean water supply).
Life expectancy is calculated by constructing a life table. A life table incorporates data on age-specific death rates for the population in question, which requires enumeration data for the number of people, and the number of deaths at each age for that population. Those numbers typically are derived from national census and vital statistics data, and from them the average life expectancy for each of the age groups within the population can be calculated.
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The potential accuracy of estimated life expectancy depends on the completeness of the census and death data available for the population in question. The completeness of that data varies from country to country. In the United States, for example, official complete life tables based on registered deaths have been prepared since 1900, in connection with the decennial census. Since 1945, annual abridged U.S. life tables have been published based on the annual death registration and estimates of the population. Complete life tables show life expectancy for every year of age, and abridged tables show life expectancy for 5- or 10-year age groups, rather than for single-year groups. National life tables for many countries are published by the United Nations in its Demographic Yearbook.
Another life expectancy calculation is healthy life expectancy (or disability-free life expectancy), which is the average number of years a person is expected to live in good health, or without disability, given current age-specific mortality rates and disease and disability prevalence rates. Calculation of those figures requires reliable health statistics as well as mortality and census data.