Research in Progress:
Exploiting Externalities to Estimate the Long-term Benefits of Early Childhood Deworming
Revised October 2014 (World Bank WPS 7052)
Abstract: This paper investigates whether a large-scale deworming intervention aimed at primary school pupils in western Kenya had long-term effects on young children in the region. The paper exploits positive externalities from the program to estimate the impact on younger children who did not receive treatment directly. Ten years after the intervention, large cognitive effects are found -- comparable to between 0.5 and 0.8 years of schooling -- for children who were less than one year old when their communities received mass deworming treatment. Because mass deworming was administered through schools, effects are estimated among children who were likely to have older siblings in schools receiving the treatment directly; in this subpopulation, effects are nearly twice as large.
Does Africa Need a Rotten Kin Theorem? Experimental Evidence from Village Economies
Joint with Pamela Jakiela, revised August 2014
(Earlier version appears as World Bank WPS 6085; also available from SSRN.)
Abstract: This paper measures the economic impacts of social pressures to share income with kin and neighbors in rural Kenyan villages. We conduct a lab experiment in which we randomly vary the observability of investment returns to test whether subjects reduce their income in order to keep it hidden. We find that women adopt an investment strategy that conceals the size of their initial endowment in the experiment, though that strategy reduces their expected earnings. This effect is largest among women with relatives attending the experiment. Parameter estimates suggest that women anticipate that observable income will be "taxed" at a rate above four percent; this effective tax rate nearly doubles when kin can observe income directly. At the village level, we find a robust association between willingness to forgo expected return to keep income hidden in the laboratory experiment, and worse economic outcomes outside the laboratory. Though this paper provides experimental evidence from a single African country - Kenya - observational studies suggest that similar kin pressures may be prevalent in many parts of the developing world.
Perils of simulation: parallel streams and the case of stata's rnormal command
November 2012 (World Bank WPS 6278)
Abstract: Large-scale simulation-based studies rely on at least three properties of pseudorandom number sequences: they behave in many ways like truly random numbers; they can be replicated; and they can be generated in parallel. There has been some divergence, however, between empirical techniques employing random numbers, and the standard battery of tests used to validate them. A random number generator that passes tests for any single stream of random numbers may fail the same tests when it is used to generate multiple streams in parallel. The lack of systematic testing of parallel streams leaves statistical software with important potential vulnerabilities. This paper shows one such vulnerability in Stata's rnormal function that went unnoticed for almost four years, and how to detect it. It then shows practical implications for the use of parallel streams in existing software.
The Impact of Secondary Schooling in Kenya: A Regression Discontinuity Analysis
Job market paper, revised January 2011
Abstract: I estimate the impacts of secondary school on human capital, occupational choice, and fertility for young adults in Kenya. Probability of admission to government secondary school rises sharply at a score close to the national mean on a standardized 8th grade examination, permitting me to estimate causal effects of schooling in a regression discontinuity framework. I combine administrative test score data with a recent survey of young adults to estimate these impacts. My results show that secondary schooling increases human capital, as measured by performance on cognitive tests included in the survey. For men, I find a drop in the probability of low-skill self-employment, as well as suggestive evidence of a rise in the probability of formal employment. The opportunity to attend secondary school also reduces teen pregnancy among women.