Visualizing Relationships - Data Points: Visualization That Means Something - page 213

FIGurE 6-32 Density plot for worldwide birth rates in 2008
Comparison
Often it's useful to compare multiple distributions rather than just the
mean, median, and mode. These summary statistics are after all descrip-
tors of the big picture. They tell you only part of a story.
For example, I could tell you that the average birth rate for the world in
2008 was 19.98 live births per 1,000 population and 32.87 in 1960, so the
birth rate was about 39 percent lower in 2008 than it was in 1960. That only
tells you what's going on in the center of the distribution though. Or is it
even the center? Are there only a few countries that had high birth rates
in 1960, bringing up the average? Did differences in birth rate increase or
decrease over the past few decades?
You can make comparisons in lots of ways. You could go entirely analytical
and not use visualization at all. (I spent a year learning about statistical
methods in graduate school, and that was just the tip of the iceberg.) You
could also go the other way and use visualization. Your results won't be an
exact answer offered by a thorough statistical analysis, but they could be
good enough to make an informed decision about whatever you're looking