This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 12th (it came out in 2015), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

If you are a user of my textbook and would like to suggest a blog post idea, please email me at: john.weeks@sdsu.edu

Sunday, November 15, 2015

With Any Luck, Your Children Will Live Longer Than You

The horrific acts of terror in Paris Friday night remind us that tragedy can strike any time, no matter how well planned our life might be. And, of course, the targeted places such as a sports stadium and rock concert are populated more by younger than older people. Still, in the aggregate, it is somewhat reassuring to remember that over the past two hundred the general trend has been for each successive cohort to live longer than preceding ones. Josh Barro of the Upshot in the NYTimes brought this up a few days ago. It is good reminder of a point I make in Chapter 5 of my text, that current life tables calculate life expectancy on the basis of period measures of mortality, whereas cohorts experience different probabilities of death as they go through life. 
According to the Centers for Disease Control and Prevention, life expectancy at birth in the United States was 78.8 years in 2013 — 76.4 years for men, 81.2 years for women. But I have good news. Those statistics don’t mean what you probably think they mean.
In fact, an American child born in 2013 will most likely live six or more years longer than those averages: boys into their early 80s, girls into their late 80s.
So this statistic [period life expectancy] is useful for measuring the health of a country’s inhabitants, but it’s not useful if what you want to know is how long your new child will live. For that, you need to look at cohort life expectancy, a statistic that adjusts for the fact that death rates tend to decline over time as health and safety improve. According to the Social Security Administration, that’s 83.1 years for boys born in the United States in 2015, and 86.8 years for girls.
As an example, my father was born in 1914, when the life expectancy for males in the U.S. was only 52.0, according to data from demographers at UC Berkeley.  When he died suddenly of a heart attack at age 67 in 1981, life expectancy for males had risen to 70.4. So, he outlived the life expectancy of his birth year, but didn't hit the life expectancy for someone born the year he died. When I was born in 1944, life expectancy for males was 63.6, and I have already lived longer than my father. My paternal grandfather, on the other hand, was born at a time when life expectancy at birth was still in the 40s, but lived to age 85 (dying at a time when life expectancy at birth had risen to 67.0) . Similarly, my maternal grandfather was born into a world of life expectancy in the 40s and lived to age 83 (at a time when life expectancy at birth had risen to 69.6). So, I have exceeded my father's longevity, but have not yet hit life expectancy at birth for a baby boy born in 2013 (76.7) and I have a ways to go to beat my grandfathers. Keep your fingers crossed for me, and I'll do the same for you.

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