Richard Lynn and Tatu Vanhanen write (large .pdf)

We do not assume that national IQ is the only factor capable to explain global disparities in access to clean water and sanitation facilities; we only assume that it is probably the most important single and measurable explanatory factor. HDR-06 does not refer to differences in national intelligence or to educational differences between nations. The report emphasizes the significance of political leadership or, rather, its absence, and secondly the importance of poverty as a barrier to progress. Our argument is that the absence of good political leadership is related to national IQ.

This is from an entire book, which seems to be easier to get on line than at Amazon. Those who disagree with the authors are not content simply to dispute their results and criticize their methods (there certainly are fair criticisms to be made). The critics want to run the authors out of the social science profession, if not the human race. That is par for the course for those who speak of the Great Unmentionable as a causal variable.

For the pointer, I thank “a miscellaneous reader from Finland,” who points out that Vanhanen is the father of the prime minister.