Mathematics
Ethnic Fractionalization and the Design of Consociational Power-Sharing Arrangements
Quick fact
The ethnic fractionalization index can range from 0 (perfectly homogeneous) to 1 (every pair is from a different group). Lebanon, with its many sects, scores around 0.75, while Japan scores near 0.01.
Why this is interesting
Imagine a country where the two largest ethnic groups each make up about half the population. How can a government be designed so that neither group fears being permanently outvoted and excluded?