Intestinal helminths–including hookworm, roundworm, whipworm, and schistosomiasis–infect more than one-quarter of the world's population. Studies in which medical treatment is randomized at the individual level potentially doubly underestimate the benefits of treatment, missing externality benefits to the comparison group from reduced disease transmission, and therefore also underestimating benefits for the treatment group. We evaluate a Kenyan project in which school-based mass treatment with deworming drugs was randomly phased into schools, rather than to individuals, allowing estimation of overall program effects. The program reduced school absenteeism in treatment schools by one-quarter, and was far cheaper than alternative ways of boosting school participation. Deworming substantially improved health and school participation among untreated children in both treatment schools and neighboring schools, and these externalities are large enough to justify fully subsidizing treatment. Yet we do not find evidence that deworming improved academic test scores.
Estimating the impact of economic conditions on the likelihood of civil conflict is difficult because of endogeneity and omitted variable bias. We use rainfall variation as an instrumental variable for economic growth in 41 African countries during 1981-99. Growth is strongly negatively related to civil conflict: a negative growth shock of five percentage points increases the likelihood of conflict by one?half the following year. We attempt to rule out other channels through which rainfall may affect conflict. Surprisingly, the impact of growth shocks on conflict is not significantly different in richer, more democratic, or more ethnically diverse countries.
This article examines how government policies affect ethnic relations by comparing outcomes across two nearby districts, one in Kenya and one in Tanzania, using colonial-era boundary placement as a "natural experiment." Despite similar geography and historical legacies, governments in Kenya and Tanzania have followed radically different language, education, and local institutional policies, with Tanzania consistently pursuing more serious nation building. The evidence suggests that nation building has allowed diverse communities in rural Tanzania to achieve considerably better local public goods outcomes than diverse communities in Kenya. To illustrate, while Kenyan communities at mean levels of diversity have 25 percent less local school funding than homogeneous communities on average, the comparable figure in the Tanzanian district is near zero. The Kenya-Tanzania comparison provides empirical evidence that serious reforms can ameliorate social divisions and suggests that nation-building should take a place on policy agendas, especially in Africa.