statistics and applied probability

national university of singapore

Radar charts

An, ahem, interesting and novel graphical display of data can be found on the MOH webpage.  It comes from a survey by Accenture of about 1000 people in each of 16 countries, including Singapore, on their perceptions of the “importance” of several health related issues and the “performance” of their national government in tackling them.  Accenture decided on a somewhat unorthodox way to present the results: via a “radar chart”.  Not heard of them before, have you?  Well, take a look at the Singapore chart:

origAppropriately, it looks like a ball. But I catch no ball!  After much contemplation, I worked out the rules for understanding it. The hours round the side aren’t hours, they indicate questions, but to find what the questions actually are, you have to scroll back 25 pages.  And the questions themselves are kind of weirdly banal:

  1. Focus on delivering real improvements in the overall health of the nation.
  2. Target health services to help people with the highest level of need.
  3. etc

So, the interviewees were asked “Do you think it’s important to focus on delivering real improvements in the overall health of the nation?” I wonder who answered no? Maybe people who like imaginary health benefits?  Or perhaps those who think the nation is already fully healthy?  Anyway, in addition, they had to say if they thought the government was performing on this issue.  Thus the graph: the radial distance from centre to the red curve indicates performance, the distance from centre to blue curve indicates desirability, and the gap indicates those people who think the government is not doing something that they think is important.

Now that you’ve understood the rules, does it make any easier to catch ball?  No, not really, cos you still have to flick back to the questions, and you’re unable to compare countries, and those distances are just hard to work out.

I wrote to Kaiser Fung of junkcharts about it, and in an extremely pithy reply, he sent the dataset Accenture used.  Taking that as a cue to do it myself, I did a makeover of the plot.  Voila!

redone1It seemed that the most important thing is to be able to compare across countries, so I switched it to focus on one question at a time.  Countries are ranked by average “performance” over the 16 questions: Singapore comes top, Ireland bottom.  The black bar is the ostensible performance, the black and red bar combined is the “importance”, and the red bar is the gap between expectations and experience.

Now, to work out why richer countries mostly do badly, while middling-income countries do well, probably requires actually reading through the report…


  1. If statisticians keep presenting results like the “radar chart”, and use those as a platform to deliver “ideas”, then more and more people are going to think that statistics is some kind of black magic that only “chosen” ones have the talents to master its “dark arts”.

    I was pretty much disinterested in statistics in high school precisely because I was exposed to too much chartjunk, LOL.

    Anyway, for the second graph it might be nice to order the countries according to the black bits. Then we can see more clearly how the red bits relate to the ranked countries.

  2. Alex

    2010/06/09 at 09:05

    I already thought about the ordering thing. The order I used was the average “performance” score over the 16 questions, so that if you were to look at all 16 plots, you wouldn’t have countries jumping about. But for a single stand alone plot, yes, I’d do the ordering the way you suggested for sure.

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