|
( Life expectancy)
Life expectancy is the expected (in the statistical sense) number of years of life remaining at a given age.[1] It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience. (In technical literature, this symbol means the average number of complete years of life remaining, excluding fractions of a year. The corresponding statistic including fractions of a year, the normal meaning of life expectancy, has a symbol with a small circle over the e.) The life expectancy of a group of individuals is heavily dependent on the criteria used to select the group. Life expectancy is usually calculated separately for males and females. Females live longer than males in countries with modern obstetric care. The term life expectancy is most often used in the context of human populations, but is also used in plant or animal ecology[2]; it is calculated by the analysis of life tables (also known as actuarial tables). The term life expectancy may also be used in the context of manufactured objects[3] although the related term shelf life is used for consumer products and the term "mean time to breakdown" (MTTB) is used in engineering literature. In countries with high infant mortality rates, the life expectancy at birth is highly sensitive to the rate of death in the first few years of life. Because of this sensitivity to infant mortality, simple life expectancy at age zero can be subject to gross misinterpretation, leading one to believe that a population with a low overall life expectancy will necessarily have a small proportion of older people. For example, in a hypothetical stationary population in which half the population dies before the age of five, but everybody else dies exactly at 70 years old, the life expectancy at age zero will be about 35 years, while about 25% of the population will be between the ages of 50 and 70. Another measure such as life expectancy at age 5 (e5) can be used to exclude the effect of infant mortality to provide a simple measure of overall mortality rates other than in early childhood—in the hypothetical population above, life expectancy at age 5 would be 70 years. Aggregate population measures such as the proportion of the population in various age classes should also be used alongside individual-based measures like formal life expectancy when analyzing population structure and dynamics. One example of this common misinterpretation can be seen in the In Search of... episode "The Man Who Would Not Die" (About Count of St. Germain) where it is stated "Evidence recently discovered in the British Museum indicates that St. Germain may have well been the long lost third son of Rákóczi born in Transylvania in 1694. If he died in Germany in 1784, he lived 90 years. The average life expectancy in the 18th century was 35 years. Fifty was a ripe old age. Ninety... was forever." This ignores the fact that life expectancy changes depending on age and the one often presented is the "at birth" number. For example, a Roman Life Expectancy table at the University of Texas shows that at birth the life expectancy was 25 but if one lived to the age of 5 one's life expectancy jumped to 48. Similar papers such as Plymouth Plantation; "Dead at Forty" and Life Expectancy by Age, 1850–2004 show dramatic increases in life expectancy after childhood.
|
Life expectancy Subcategories
Making it Happen - Taking Action to Change Your Life > >
Life expectancy Articles
The Push for Supplements for the Brain by ActiveCell Power
If you could be offered a pill to stave off the effects of aging you would be sure to take it. Aging quietly into a decrepit state is no longer seen as acceptable. There is a huge push for research to counteract the effects of aging. Life expectan...
The Background of the Best Brain Supplements by ActiveCell Power
Taking a simple pill that could make you feel ten years younger seems like a pipe dream. Well, research has been done to develop supplements that can make this happen. The US Life Nutrition Academy of Sciences (AIBNS) has developed one of the best...
|
|
