Alternative Measures of Age
Gains in life expectancy have changed our understanding of aging.
When the Social Security Act of 1935 set the minimum retirement age at 65, the average 65-year-old man could expect to live another 11.9 years. A man retiring at 65 today can expect to live another 18 years or more, an increase that has a sizeable impact on retirement policy.
Age in relation to life expectancy matters for many policy research questions beyond retirement, including those concerning health and employment. Life expectancy makes a big difference when asking such questions as whether people are working longer or whether they are getting healthier over time.
To control for the rise in life expectancy, we created two alternative measures of age: the life expectancy age and the relative life expectancy age.
- Life expectancy age. Depending on the research question, measuring age as the distance to the end of life may be more informative than measuring it as the distance from birth (which is what chronological age measures). With this alternative measure, we keep life expectancy fixed.
For example, a 65-year-old woman in 2010 has a life expectancy of 20.2 years. Her equivalent in 1960 would be a 59.2-year-old woman because she also has a life expectancy of 20.2 years.
- Relative life expectancy age. This measure reflects a relative position in the life cycle. With this measure, we look at remaining life expectancy as a share of the life span. We define this as the ratio of a person's remaining life expectancy to his or her total expected life span (which is age plus life expectancy).
For example, a 65-year-old woman in 2010 with a life expectancy of 20.2 years has a relative life expectancy of 0.24, meaning that her remaining years will make up 24 percent of her life. Her equivalent in 1960 is a 60.9-year-old woman whose life expectancy is 18.9 years and who therefore also has a relative life expectancy of 0.24.
Using these alternative measures of age can fundamentally alter many conclusions in economic and demographic studies of aging and age-related policies.
How to use this tool
Researchers can use this site to easily convert chronological age to the two alternative measurements of age and vice versa. The following pages present interactive charts and downloadable tables that show the relationship between different measures of age. We also offer a case study that uses these alternative measures to look at employment over time.
How Alternative Measures of Age Can Profoundly Affect Research Conclusions
Damir Cosic and Eugene Steuerle
About the project
The relationship between age, life expectancy, and calendar year used to calculate these alternative measures of age was obtained from the Period Life Tables published by the Social Security Administration. Employment rates were estimated from the Current Population Survey data obtained from the Integrated Public Use Microdata Series Current Population Survey from the Minnesota Population Center at the University of Minnesota. This work was funded by the Alfred P. Sloan Foundation.
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