This is cool chart #2.
Hans Rosling graphs life expectancy vs. income per capita for 200 countries in a bubble chart animated over time. The size of the bubbles represent population. Bigger bubbles-bigger countries. The countries are also color-coded by region. So this chart has 5 dimensions: life expectancy, income, population size, region, and time.
While watching this presentation, notice the X axis which has a log scale. This scale is used for two reasons. First, if it were linear, most of the countries would be tightly grouped at the left given the skewed distribution of income with a fewer outliers at the right. Second, the log scale emphasizes the rate of economic change within developing countries. Historically, per capital income doesn’t grow linearly but seems to happen in bursts (e.g., China and India).
I like the way that Rosling shows that rates of change in some countries are highly differential by splitting out rich and poor regions. This is a classic form of data drill-down–except in this case it is represented by popping bubbles.
The life expectancy rate is definitely outpacing the income rate. Sadly, most of Africa is left behind on the income variable.
Many thanks to Art Kendall for publicizing this chart on the SPSSX-L list.