A recurring theme on vX is that governments often don’t collect, or actively suppress, data they don’t want the world to see.
The worst example is North Korea:
"Trying to describe North Korea statistically for a statistician is like [climbing] Mount Everest," said Nicholas Eberstadt, a demographer at the American Enterprise Institute, a conservative Washington, D.C., think tank. "It's the last place on earth where one can't find regular, reliable data on a national scale."
Other countries have statistical data that are incomplete, but "normally they fall into the category of extremely poor or failed states," Dr. Noland said. "Our statistical understanding of North Korea is very poor as a matter of state policy."
The country ceased publishing statistical yearbooks a half century ago, said Daniel J. Schwekendiek, an economist at Sungkyunkwan University in Seoul. Dr. Schwekendiek said he generally finds what sparse North Korean data exist to be of good quality. …
Read the whole thing, entitled “Putting Statistics to Work in a Land of Illusions” in the January 19 issue of The Wall Street Journal.