计量经济分析 = Econometric analysis

A common approach to evaluating robustness to omitted variable bias is to observe coefficient movements after inclusion of controls. This is informative only if selection on observables is informative about selection on unobservables. Although this link is known in theory in existing literature, very few empirical articles approach this formally. I develop an extension of the theory that connects bias explicitly to coefficient stability. I show that it is necessary to take into account coefficient and R-squared movements. I develop a formal bounding argument. I show two validation exercises and discuss application to the economics literature. Supplementary materials for this article are available online.

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Unobservable Selection and Coefficient Stability: Theory and Evidence

Ethnic Groups in Conflict

Citizen and Subject: Contemporary Africa and the legacy of late colonialism

In a recent study, Nunn (2008) examines the long-term impacts of Africa’s slave trade. He finds that the slave trade, which occurred over a period of more than 400 years, had a significant negative effect on long-term economic development. Although the article arguably identifies a negative causal relationship between the slave trade and income today, the analysis is unable to establish the exact causal mechanisms underlying this reduced-form relationship. In this article, we examine one of the channels through which the slave trade may affect economic development today. Combining contemporary individual-level survey data with historical data on slave shipments by ethnic group, we ask whether the slave trade caused a culture of mistrust to develop within Africa. Initially, slaves were captured primarily through state organized raids and warfare, but as the trade progressed, the environment of ubiquitous insecurity caused individuals to turn on others—including friends and family members—and to kidnap, trick, and sell each other into slavery (Sigismund Wilhelm Koelle 1854; P. E. H. Hair 1965; Charles Piot 1996). We hypothesize that in this environment, a culture of mistrust may have evolved, which may persist to this day. We show that current differences in trust levels within Africa can be traced back to the transatlantic and Indian Ocean slave trades. Combining contemporary individual-level survey data with historical data on slave shipments by ethnic group, we find that individuals whose ancestors were heavily raided during the slave trade are less trusting today. Evidence from a variety of identification strategies suggests that the relationship is causal. Examining causal mechanisms, we show that most of the impact of the slave trade is through factors that are internal to the individual, such as cultural norms, beliefs, and values. (JEL J15, N57, Z13)

/pdf/the-slave-trade-and-the-origins-of-mistrust-in-africa-1si0ln9pu8.pdf

The Slave Trade and the Origins of Mistrust in Africa

We investigate the role of deeply rooted pre-colonial ethnic institutions in shaping comparative regional development within African countries. We combine information on the spatial distribution of ethnicities before colonization with regional variation in contemporary economic performance, as proxied by satellite images of light density at night. We document a strong association between pre-colonial ethnic political centralization and regional development. This pattern is not driven by differences in local geographic features or by other observable ethnic-specific cultural and economic variables. The strong positive association between pre-colonial political complexity and contemporary development also holds within pairs of adjacent ethnic homelands with different legacies of pre-colonial political institutions.

/pdf/pre-colonial-ethnic-institutions-and-contemporary-african-146jk0svzg.pdf

Pre-colonial Ethnic Institutions and Contemporary African Development

We investigate the role of national institutions on subnational African development in a novel framework that accounts both for local geography and cultural-genetic traits. We exploit the fact that the political boundaries in the eve of African independence partitioned more than two hundred ethnic groups across adjacent countries subjecting similar cultures, residing in homogeneous geographic areas, to different formal institutions. Using both a matching-type and a spatial regression discontinuity approach we show that differences in countrywide institutional structures across the national border do not explain within-ethnicity differences in economic performance, as captured by satellite images of light density. The average non-effect of national institutions on ethnic development masks considerable heterogeneity partially driven by the diminishing role of national institutions in areas further from the capital cities.

National Institutions and Subnational Development in Africa

/pdf/national-institutions-and-subnational-development-in-africa-4q9jckm2ur.pdf

This research examines the economic origins of ethnolinguistic diversity. The empirical analysis constructs detailed data on the distribution of land quality and elevation across contiguous regions, virtual and real countries, and shows that variation in elevation and land quality has contributed significantly to the emergence and persistence of ethnic fractionalization. The empirical and historical evidence is consistent with the proposed hypothesis, according to which heterogeneous land endowments generated region specific human capital, limiting population mobility and leading to the formation of localized ethnicities and languages. The research contributes to the understanding of the emergence of ethnicities and their spatial distribution and offers a distinction between the natural, geographically driven, versus the artificial, man-made, components of contemporary ethnic diversity.

The Origins of Ethnolinguistic Diversity

This study explores the determinants of ethnolinguistic diversity within as well as across countries, shedding light on its geographic origins. The empirical analysis conducted across countries, virtual countries, and pairs of contiguous regions establishes that geographic variability, captured by variation in regional land quality and elevation, is a fundamental determinant of contemporary linguistic diversity. The findings are consistent with the proposed hypothesis that differences in land endowments gave rise to location-specific human capital, leading to the formation of localized ethnicities. (JEL J15, J24, Z13)

/pdf/the-origins-of-ethnolinguistic-diversity-44kyv9vzn1.pdf

Stelios Michalopoulos

Papers

Pre-colonial Ethnic Institutions and Contemporary African Development

National Institutions and Subnational Development in Africa

National Institutions and Subnational Development in Africa

The Origins of Ethnolinguistic Diversity

The Origins of Ethnolinguistic Diversity