He finds, in his instrumental variables regressions, that economic variables, such as the
log of GDP per capita or the human development index are not significant determinants of country
terrorism risk, that while linguistic fractionalization increases the risk of terrorism, ethic
fractionalization, or religious fractionalization do not seem to matter, that, three geographic and
climatic variables, country area, country elevation, and the fraction of the country in the tropics, each
have a positive and significant effect on the risk of country terrorism, and finally, that there appears to
exist a nonlinear hump shaped relationship between the risk of terrorism and the lack of political rights