It is no secret that I am very interested in data visualisation, and yet I have never mentioned the work of Hans Rosling here on the blog. It is an omission I should finally correct, not least to acknowledge those readers who regularly email me links to Rosling’s videos.
Rosling is a doctor with a particular interest in global health and welfare trends. In an effort to broaden awareness of these trends, he founded the non-profit organisation Gapminder, which is described as:
a modern “museum” on the Internet – promoting sustainable global development and achievement of the United Nations Millennium Development Goals
Gapminder provides a rich repository of statistics from a wide range of sources and it was at Gapminder that Rosling’s famous animated bubble charting tool Trendalyzer was developed. I first saw Trendalyzer in action a number of years ago in a presentation Rosling gave at a TED conference. Rosling continued to update his presentation and there are now seven TED videos available. But, the video that Mule readers most often send me is the one below, taken from the BBC documentary “The Joy of Stats”.
If the four minutes of video here have whetted your appetite, the entire hour-long documentary is available on the Gapminder website. You can also take a closer look at Trendalyzer in action at Gapminder World.
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That’s a quite colorful explanation. And as the presenter says, it’s a pretty neat way of displaying large sets of data.
But there’s a detail that troubles me: the horizontal scale is logarithmic.
The general aggregate movement of the cloud, considering this scale, appears to be occurring in the northeast direction.
But in a non-logarithmic scale (assuming the monetary values are constant dollars), the movement is more similar to an upper case gamma: first in a relatively more northward direction, then almost due east.
Follow, for instance, China and India (the two biggest red balls), as they are easier to distinguish. They also appear to follow the pattern mentioned above more clearly.
When China and India start “moving”, after WW2, they move vertically (India more slowly; China faster, but wobbling up and down, during the 50s-60s). According to this, one should conclude that Mao’s triumph, for some reason, had a positive effect in Chinese longevity, even though it did not increase Chinese average (is average income, I take it) income.
Following with China, it appears that the following period of opening towards Western style capitalism may have increased average incomes quite remarkably (particularly in the case of Shanghai, that Rosling emphasizes), with a comparably much slower improvement in longevity.
Further, when one focuses in the whole cloud, the effect of the logarithmic scale is to present the cloud as relatively “constantly dense”, when in reality the density diminishes as we move eastwards.
I wonder if one could interpret this in the following way: (1) Economic development may bring improvements in living conditions, in a manner of speech, as an afterthought or an unintended consequence. (2) And it may have a diminishing marginal effect.
Yes I noticed the log scale too. There are a few common reasons for using log scale. One is simply to deal with too much dispersion at one end of the scale. Another is if the relationship seems to fit. In this case, for example, it may be that the points more closely approximate a straight line with a log scale than with the original units.
One thing about it that intrigues me is that I have often read that when it comes to differences of income, relative differences are important rather than absolute differences. Since on a log scale, incomes which differ by a factor of two (eg $4000 vs $8000 and $8000 vs $16000) are the same distance apart, perhaps it is actually a useful scale insofar as it shows relative differences in income.
That’s just my speculation: it would be interesting to see whether Gapminder or Rosling have anything to say about it anywhere.
I don’t think this should be interpreted as anything other than that was a presentation made for what I suppose is a documentary (as opposed to an academic presentation): the producers might have tried to emphasize the capabilities of the software, without complications due to the analysis of the data.
Regardless, do you agree with the observations in my first comment?
Any other reader would care to comment?