Ethnic diversity and conflict
研究发现，族群极化而非碎片化对经济表现和冲突的负面影响，仅在多样性超过一定阈值时才显著；国家层面的高碎片化常伴随少数族群区域集中，导致局部极化加剧，冲突更可能局限于特定地理区域。
Abstract We argue that the reason why it has proved hard to determine whether negative effects on economic performance and conflict are more strongly associated with polarized rather than fractionalized societies is because the distinction between polarization and fractionalization is only relevant for societies with ethnic diversity above a certain threshold. In addition, high levels of ethnic fractionalization at a country level are generally associated with regional concentration of minorities, and as a result, many regions may have a very different ethnic composition from the national average, and in particular, they may have much higher levels of ethnic polarization than the national level. Because of the very different ethnic composition of different regions in this situation, conflict is more likely to be confined to a limited geographical area.