  Many countries are ethnically diverse. However, despite the benefits of
ethnic heterogeneity, ethnic-based political inequality and discrimination are
pervasive. Why is this? This study suggests that part of the variation in
ethnic-based political inequality depends on the relative size of ethnic groups
within each country. Using group-level data for 569 ethnic groups in 175
countries from 1946 to 2017, I find evidence of an inverted-U-shaped
relationship between an ethnic group's relative size and its access to power.
This single-peaked relationship is robust to many alternative specifications,
and a battery of robustness checks suggests that relative size influences
access to power. Through a very simple model, I propose an explanation based on
an initial high level of political inequality, and on the incentives that more
powerful groups have to continue limiting other groups' access to power. This
explanation incorporates essential elements of several existing theories on the
relationship between group size and discrimination, and suggests a new
empirical prediction: the single-peaked pattern should be weaker in countries
where political institutions have historically been less open. This additional
prediction is supported by the data.

General Economics;Economics