"Life Expectancy" Doesn't Measure How Long You're Expected To Live

This is a great post. Because I'm a nerd, I'm compelled to make an orthogonal point:<p>Life expectancy is not entirely medical and is not a particularly good way to compare countries. Consider that among the top causes of death in the US are "accidents" (predominantly motor vehicles) and suicide, both of which are anomalously high in the US.<p>Consider also that if you go to the top US cause of death (heart disease, clearly medical) and then compare the world rankings for heart disease deaths, you'll find many of the countries that beat the US in the life expectancy rankings do worse than the US in the heart disease mortality rankings.<p>You'll tend to see similar effects for other medical issues, particularly cancer, in which the US notoriously outperforms many of the European countries that outrank it on life expectancy.

Other than the cohort and period life expectancy, what is imp. to most people should be something else:<p>* How many more years do you expect to live if you are already X years old in 2012?<p>This is obviously different than just calculating from the cohort life expectancy of 2012-X since you you've already passed the vulnerable infancy stage. Also, say you are 90 today, so your cohort exp, for 1922 births must be something like, say 80. Your expectation of living more is certainly not -10 years!

A very interesting post indeed. Another common mistake many people seem to make is when comparing historical life expectancies. Most of our progress in prolonging human life is due to minimizing the infant mortality rate. This means that people who survived infancy and childhood could make it to an old age even in historical times.

Also life expectancy changes as you age: <a href="http://www.ssa.gov/oact/STATS/table4c6.html" rel="nofollow">http://www.ssa.gov/oact/STATS/table4c6.html</a><p>By the time you hit 60, you've gone from ~75 to ~80.

I don't like using averages because they can be misleading. A triplet of the 25th, 50th and 75th percentiles is more descriptive. Of course, the most complete picture is looking at the whole distribution.<p>I'd like to see a plot of the distribution of lifetime as a function of birth year. I.e. a 3D plot with current age on the X axis, age of death on the Z axis, and probability on the Y axis. (Where, as in Minecraft, X is east/west, Z is south/north.)<p>Cut off the portion representing people who have died already (Z &#60; now-X), renormalize each cohort so its Y values add up to 1, and you'll get the distribution of lifetimes for people who are alive today. (I.e. a conditional distribution, conditioned on being alive today.) Which at least one other poster was asking about.

Just last week there was another Hacker News post that prompted me to look up some of the articles by demographer James W. Vaupel, one of the leading scholars on the demography of aging and how to adjust for time trends in life expectancy. His article<p>"Biodemography of human ageing" Nature. 2010 Mar 25;464(7288):536-42. doi:10.1038/nature08984<p><a href="http://www.demographic-challenge.com/files/downloads/2eb51e2860ef54d218ce5ce19abe6a59/dc_biodemography_of_human_ageing_nature_2010_vaupel.pdf" rel="nofollow">http://www.demographic-challenge.com/files/downloads/2eb51e2...</a><p>covers most of the essential issues. His striking finding is "Humans are living longer than ever before. In fact, newborn children in high-income countries can expect to live to more than 100 years. Starting in the mid-1800s, human longevity has increased dramatically and life expectancy is increasing by an average of six hours a day."<p><a href="http://www.prb.org/Journalists/Webcasts/2010/humanlongevity.aspx" rel="nofollow">http://www.prb.org/Journalists/Webcasts/2010/humanlongevity....</a><p>Meanwhile, a person at any given age can look up period life tables for what the blog post author of the post submitted here correctly describes as a MINIMUM life expectancy at that person's current age.<p><a href="http://www.ssa.gov/oact/STATS/table4c6.html" rel="nofollow">http://www.ssa.gov/oact/STATS/table4c6.html</a><p><a href="http://www.infoplease.com/ipa/A0005140.html" rel="nofollow">http://www.infoplease.com/ipa/A0005140.html</a><p>(The links shown are for United States data, but data like these are available for most developed countries.)<p>It is also possible to find life expectancy formulas adjusted for personal health status and lifestyle.<p><a href="http://www.msrs.state.mn.us/info/Age_Cal.htmls" rel="nofollow">http://www.msrs.state.mn.us/info/Age_Cal.htmls</a><p>(Minnesota data)<p><a href="http://www.bupa.com.au/health-and-wellness/tools-and-apps/tools-and-calculators/quick-health-age-check" rel="nofollow">http://www.bupa.com.au/health-and-wellness/tools-and-apps/to...</a><p>(Australia data)<p>The link posted last week<p><a href="http://www.scientificamerican.com/article.cfm?id=longevity-why-we-die-global-life-expectancy" rel="nofollow">http://www.scientificamerican.com/article.cfm?id=longevity-w...</a><p>gives good data on trends in causes of death from 1960 to the present in the United States and in OECD countries as a whole. It showed that life expectancy at birth, at age 40, at age 60, at age 65, and at age 80 have all increased during the years shown on the chart.

The "rectangularisation of the life curve", i.e. a cohort facing low mortality (thanks to better social practices and healthcare) until a ripe old age when it starts dramatically dying off, implies a maximum human lifespan that we have not significantly manipulated in the history of human biology.

Thanks for making me realize I've been using life expectancy tables incorrectly for most of my life.<p>One comment regarding the yearly progress of the cohort rate. I would think this would fluctuate with significant medical advances (e.g. the first few years that bypass surgery/artificial hearts started to be used). I can't see how medical progression is perfectly linear at 1.0%/year.

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When looking at these numbers, and thinking how the official retirement age in most countries has been raised to 67 or 69, does anyone else feel like old Boxer from Animal Farm [1] ?<p>They keep dangling that retirement carrot in front of us, but by the time we get to enjoy it, we're dead.<p>[1]en.wikipedia.org/wiki/Boxer_(Animal_Farm)