## Two easy pieces

##### Jan 16, 2006

One

The life-expectancy chart (top right) gives the false impression that men live half as long as women.  The problem is easily fixed using the start-at-zero rule, as shown in the bottom chart.

Demographers use a side-by-side bar chart (known as a population pyramid) to plot such data.  A variation is shown.  This construct facilitates inter-country comparisons but is less than effective here because the ages are bunched together.

Of interest in this data is whether the female/male life expectancy gap is constant across countries.  The last graph in this series shows which countries are above or below the group average; in each country, women live on average at least ~6% longer.

Reference: BBC News website (thanks to Tom for the tip-off)

Two

Here is a great use of a line chart.  The clear message is that Toyota (and to a lesser extent, Japanese auto-makers) are relying less on price-cutting to attract customers than the Americans.  Particular praise should be given to the judicious and spare choice of axis markers.

Reference: "Toyota Shows the Big 3 ...", New York Times, Jan 13 2006.

### Comments

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Take your graph of female/male life expectancy ratio and rotate it 90 degrees. That way you can spell out the country names and it's much more readable.

Actually, I'd also change the scale to difference in years rather than life expectancy ratio; the numbers are all close enough that there's no real need to divide, and years are clearer than ratios.

Population pyramids are used to show sex-specific age distributions, not to show country-specific life expectancies.

The bottom chart appear to be ordered by male life expectancy. If the point is that female life expectancy is higher, you might want to re-order by the gap. Alternatively, you could do a Tukey mean-difference plot. Here's one; here's another.

This nice posting reminds me of a slightly different type of comparisons in the statgraphics blog.

Great points Andrew. I like them both.

Robert, the Tukey mean-difference plot is conceptually similar to my plot except that it introduces a ranking on the x-axis. This does bring up another improvement to the plot which is that it'd be better to have sorted the countries in terms of increasing differences.

Finally, Aleks pointer to statgraphics currently has a dizzingly bad map from Forbes magazine. Fun to look at though

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