Department of Awful Statistics

By Megan McArdle

That widely circulated map showing that the US "human development index" varies widely by state and, oddly enough, just happens to show that the most liberal states generally have the most developed human beings, turns out to be bunk.  I'll let James Joyner summarize:



It turns out that the "index" considers only three elements:  Life expectancy at birth, Adult literacy and education, and a variant of GDP per capita.   It turns out that the first two of these are so uniform across the 50 states as to be negligible, making the last the main determinant of the ranking.  Additionally, Mississippi's .799 makes it just barely fit into the arbitrary color breakdowns, making it appear to those looking at the map to be massively less "developed" than West Virginia and Louisiana, at .800 and .801, respectively.

What Gelman does not add is that "the natural logarithm of gross domestic product (GDP) per capita at purchasing power parity (PPP) in United States dollars" is actually a rather poor measure of "standard of living" given that it's not normalized for local housing prices.

Does anyone really think that there's a significantly different level of "development" between North and South Carolina?  Or that Michigan is better off than Missouri?

Joyner adds:  "This is yet another instance of a trend that I've long found aggravating: the ordinal ranking of relatively similar bodies to create the illusion of substantial disparity.  We usually see it in the form of international comparisons, which have the United States ranked 35th on some attribute despite being essentially the same as the country ranked 1st. "

Blue states are indeed richer.  But presumably the liberals who gave this map link love don't think per capita GDP is actually a really good measure of human development.




This article available online at:

http://www.theatlantic.com/business/archive/2009/05/department-of-awful-statistics/18014/