Old statisticians never die - they just get broken down by age and sex.  

Mind the Gap

Several years ago I posted a graphic plotting country’s GDP per head against mean lifetime and drawing attention to the tragic loss of life in southern Africa, mainly due to AIDS. There is a fantastic data visualisation tool called GapMinder that tells this story – and other  stories-  much more clearly. And it is really fun to play with.

Click HERE to open the tool in another window at a much sexier version of the original graphic (for the year 2007).  You need Flash 7 and it may take 30 seconds to load but it is worth the wait.

A quick explanation. Each point is a country and upper right means high GDP and high life expectancy. GDP is on a log-scale partly because the distribution is so skew, but also because the relationship is almost linear that way. Colours are different continents – with Africa in blue. Size of the blob is population size – probably not of primary interest here. But the really cool thing here is the last dimension – time. Move the slider back to 1800 and hit the play button to see the data displayed in sequence for the past 200 years.

My original interest in these data was the AIDS epidemic in Africa. Focusing on the blue swarm of African nations, you will see that there was virtually no improvement in life expectancy until after WW2. Over the past 30 years however, you will also see the blue swarm stagnate to the bottom left. Then, during the past decade about 10 middle income countries just drop through the floor. Pretty stark it is.

You can follow individual countries just by clicking on them (or on their name in the list at the right). Below is the trajectory for Iraq. What do you think happened in 1979?

Other countries whose trajectory has a story to tell - Rwanda but ther civil war was devastating it  pre-genocide (1994), Chile which did well after Pinochet (1974) but was doing extremely well in terms of life expectancy before 1974. Check out Russia…it hardly looks like the wall coming down was a resounding success.

Let’s get parochial. Apart from minor glitches after the great depression and WW2, Australia has enjoyed an uninteresting march towards wealth and health. Give me a boring trajectory any old time. For those who ever doubted that NZ was the eighth state, look at their trajectory at the same time as ours. Peas in a pod.

China watchers might like to focus on the middle kingdom around the late 1950’s. I was actually impressed that they managed to get data on life expectancy from a nation that does not like its dirty linen aired. But this thought process led me to a more obvious question - what does life expectancy mean for 2007? This has to be a model projection - it is not really data at all. So I checked the documentation and it is defined as “the number of years a newborn child would live if current mortality patterns were to stay the same.” In China’s case then this would mean that the drop we see is an extrapolation of what would have happened if the great leap forward continued indefinitely. Ditto Rwanda. It is certainly not the case that the babies who were born in Rwanda in 1991 will have a mean life of 24 years.

I look forward to the inclusion of 2008 and 2009 data so we can see the ffect of the GFC and how it is differentially felt in different countries. Look out for the Icelandic bubble to bounce faster than Novak Jokivich’s service routine.  You can waste hours playing with this site. There is a huge range of economic, environmental, health, education and demographic measured to select from.

If you want to use this tool for your own data.. .. you can’t. But GapMinder suggest using Motion Chart, which is a free gadget in Google Spreadsheet (an online spreadsheet similar to excel).


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5 Responses to “Mind the Gap”

  1. Bruce Tabor Says:

    Until I had to calculate “life expectancy at birth” for the NSW Health biannual Chief Health Officer’s Report, I was confused how it could be calculated with such precision. Then I found it is calculated using the population structure and death rates of people in the year (or years - I think the ABS uses 2 years) for which it is calculated.

    Some points:
    1) It is an average & hence is highly sensitive to infant mortality.
    2) It is an average and hence the median life expectancy is in fact higher than the life expectancy.
    3) Your expected age of death (i.e age plus life expectancy) will rise continuously as you age, provided mortality patterns stay the same.
    4) Rather disappointingly, you will always have some life expectancy left in you when you die (statistically speaking), no matter what age you die. (lies, damned lies and…)

    I thought the chart showed we are the lucky country. Nothing but rising per capita GDP and mostly rising life expectancy since 1946 - which I suspect is the entire span of the living memory of most readers of this blog. The only significant setbacks since 1866 (when life expectancy starts moving) were economic contractions in the 1890s, the 1930s and a short end of WW2 blip. In spite of WW1 there was no reduction in life expectancy unlike the UK, Germany etc.

    Many countries zig-zag (Argentina) and even do loops (Japan). Even the US had a crash in life expectancy in 1918, probably due to the Spanish flu. (We got a mild version in 1919.) Can you imaging the internal pressures in nations when these events occur?

  2. Chris Lloyd Says:

    I love it! “You will always have some life expectancy left in you when you die.” What a waste!

  3. Bruce Tabor Says:

    Life expectancies are calculated using life tables. See here for a recent ABS one done by sex and age in years up to 100:
    http://www.abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/3302.0.55.0012005%E2%80%932007?OpenDocument
    (Click “Download Excel File”) and choose the worksheet “Table_1″ by clicking the tab on the lower left. The column “ex” gives the life expectancy at each age. A glossary can be found here:
    http://www.abs.gov.au/ausstats/abs@.nsf/exnote/3302.0.55.001

    Maybe we should keep this under our hat! I can just imaging if this gets out. “My Grandpa died last week. He was 85 years old. We’re going to sue the ABS because they say he should have lived another 6 years!”

  4. Hi Chris,

    Similar capabilities have been used to great effect by Hans Rosling at TED. I often use this presentation at work to show the perils of profiling via means.

    http://www.ted.com/talks/lang/eng/hans_rosling_shows_the_best_stats_you_ve_ever_seen.html

  5. The Hans Rosling lecture is indeed quite provocative. Thank you, Anthony for the recommendation!

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