In Exercise 23 we saw that the United Nations Development Programme (UNDP) uses the Human Development Index (HDI) in an attempt to summarize the progress in health, education, and economics of a country with one number. The gross domestic product per capita (GDPPC) attempts to summarize the wealth produced by a country in one number. Here is a plot of GDPPC against HDI:

GDPPC is measured in dollars. Incomes and other economic measures tend to be highly right skewed. Taking logs often makes the distribution more unimodal and sym-metric. Compare the histogram of GDPPC to the histogram of log (GDPPC).

60,000 40,000 20,000 0.45 060 0.75 0.90 HDi