Can Having Fewer Partners Increase Prevalence of Aids?

Under asymmetric information about sexual history, sexual activity creates externalities. Abstinence by those with few partners perversely increases the average probability of HIV infection in the pool of available partners. Since this increases prevalence among the high activity people who disproportionately influence the disease's future spread, it may increase long-run prevalence. Preliminary calculations using standard epidemiological models and survey data on sexual activity suggest that most people have few enough partners that further reductions would increase steady-state prevalence. To the extent the results prove robust, they suggest that public health messages will be more likely to reduce steady-state prevalence and create positive externalities if they stress condom use rather than abstinence.

Worms: Education and Health Externalities in Kenya

Intestinal helminths - including hookworm, roundworm, schistosomiasis, and whipworm - infect more than one-quarter of the world's population. A randomized evaluation of a project in Kenya suggests that school-based mass treatment with deworming drugs reduced school absenteeism in treatment schools by one quarter; gains are especially large among the youngest children. Deworming is found to be cheaper than alternative ways of boosting school participation. By reducing disease transmission, deworming creates substantial externality health and school participation benefits among untreated children in the treatment schools and among children in neighboring schools. These externalities are large enough to justify fully subsidizing treatment. We do not find evidence that deworming improves academic test scores. Existing experimental studies, in which treatment is randomized among individuals in the same school, find small and insignificant deworming treatment effects on education; however, these studies underestimate true treatment effects if deworming creates positive externalities for the control group and reduces treatment group attrition.

Schools meals, educational achievement and school competition: evidence from a randomized evaluation

This paper examines the effects of subsidized school meals on school participation, educational achievement, and school finance in a developing country setting. The paper uses data from a program that was implemented in 25 randomly chosen preschools in a pool of 50. Children's school participation was 30 percent higher in the treatment group than in the comparison group. The meals program led to higher curriculum test scores, but only in schools where the teacher was relatively experienced prior to the program. The school meals displaced teaching time and led to larger class sizes. Despite improved incentives, teacher absenteeism remained at a high level of 30 percent. Treatment schools raised their fees, and comparison schools close to treatment schools decreased their fees. Some of the price effects are due to a combination of capacity constraints and pupil transfers that would not happen if the school meals were offered in all schools. The intention-to-treat estimator of the effect of the randomized program incorporates those price effects, and therefore it should be considered a lower bound on the effect of generalized school meals. This insight on price effects generalizes to other randomized program evaluations.School Health,Public Health Promotion,Teaching and Learning,Primary Education,Health Monitoring&Evaluation,Primary Education,Health Monitoring&Evaluation,Teaching and Learning,Gender and Education,Adolescent Health

The Illusion of Sustainability

The history of foreign development assistance is one of movement away from addressing immediate needs and toward focusing on the underlying causes of poverty. A recent manifestation is the move towards sustainability,' which stresses community mobilization, education, and cost-recovery. This stands in contrast to the traditional economic analysis of development projects, with its focus on providing public goods and correcting externalities. We examine evidence from randomized evaluations on strategies for combating intestinal worms, which affect one in four people worldwide. Providing medicine to treat worms was extremely cost effective, although medicine must be provided twice per year indefinitely to keep children worm-free. An effort to promote sustainability by educating Kenyan schoolchildren on worm prevention was ineffective, and a mobilization' intervention from psychology failed to boost deworming drug take-up. Take-up was highly sensitive to drug cost: a small increase in cost led to an 80 percent reduction in take-up (relative to free treatment). The results suggest that, in the context we examine, the pursuit of sustainability may be an illusion, and that in the short-run, at least, external subsidies will remain necessary.

Elephants

Existing models of open-access resources are applicable to non-storable resources, such as fish. Many open-access resources, however, are used to produce storable goods. Elephants, rhinos, and tigers are three prominent examples. Anticipated future scarcity of these resources will increase current prices, and current poaching. This implies that, for given initial conditions, there may be rational expectations equilibria leading both to extinction and to survival. Governments may be able to eliminate extinction equilibria by promising to implement tough anti-poaching measures if the population falls below a threshold. Alternatively, they, or private agents, may be able to eliminate extinction equilibria by accumulating a sufficient stockpile of the storable good.

Wage Inequality and Segregation by Skill

Evidence from the US, Britain, and France suggests that recent growth in wage inequality has been accompanied by greater segregation of high- and low-skill workers into separate firms. A model in which workers of different skill-levels are imperfect substitutes can simultaneously account for these increases in segregation and inequality either through technological change, or, more parsimoniously, through observed changes in the skill-distribution