Commentary. Fixed effects and risks of miscommunication: a comment on Jullien, Sinclair and Garner (ungated copy)
International Journal of Epidemiology, (February 2017)
The Impact of Secondary Schooling in Kenya: A Regression Discontinuity Analysis
Journal of Human Resources, accepted September 2016.
(Appears as World Bank WPS 7384; also available from SSRN.)
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.
Does Africa Need a Rotten Kin Theorem? Experimental Evidence from Village Economies
Review of Economic Studies (2016) 83 (1): 231-268
Joint with Pamela Jakiela
(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.
Data and analysis files (hosted at the World Bank Microdata Catalog)
Monitoring and evaluating the impact of national school-based deworming in Kenya: study design and baseline results
Parasites and Vectors (2013 July) 6:198
Joint with CS Mwandawiro, B Nikolay, JH Kihara, DA Mukoko, MT Mwanje, A Hakobyan, RL Pullan, SJ Brooker, SM Njenga
Abstract: An increasing number of countries in Africa and elsewhere are developing national plans for the control of neglected tropical diseases. A key component of such plans is school-based deworming (SBD) for the control of soil-transmitted helminths (STHs) and schistosomiasis. Monitoring and evaluation (M&E) of national programmes is essential to ensure they are achieving their stated aims and to evaluate when to reduce the frequency of treatment or when to halt it altogether. The article describes the M&E design of the Kenya national SBD programme and presents results from the baseline survey conducted in early 2012.
A Firm of One's Own: Experimental Evidence on Credit Constraints and Occupational Choice
February 2017 (World Bank WPS 7977); Joint with Andrew Brudevold-Newman, Maddalena Honorati, and Pamela Jakiela
(Also appears as IZA Discussion Paper 10583.)
November 2012 Blog Post at All About Finance: Microfranchising in Nairobi hits the BBC
PEDL Pilot Study Research Note
Trial Registry AEARCTR-0000459
The Impact of Violence on Individual Risk Preferences: Evidence from a Natural Experiment
Revised April 2016 as IZA Discussion Paper 9870; Joint with Pamela Jakiela
(Earlier version appears as World Bank WPS 7440; also appears as Households in Conflict Network working paper 204; also available from SSRN.)
Abstract: We estimate the impact of Kenya's post-election violence on individual risk preferences. Because the crisis interrupted a longitudinal survey of more than five thousand Kenyan youth, this timing creates plausibly exogenous variation in exposure to civil conflict by the time of the survey. We measure individual risk preferences using hypothetical lottery choice questions which we validate by showing that they predict migration and entrepreneurship in the cross-section. Our results indicate that the post-election violence sharply increased individual risk aversion. Findings remain robust when we use an IV estimation strategy that exploits random assignment of respondents to waves of surveying.
Exploiting Externalities to Estimate the Long-term Benefits of Early Childhood Deworming
Revised July 2016; revision requested
(Earlier version appears as World Bank WPS 7052; also available from SSRN.)
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.
September 2015 World Bank Evidence to Policy note: KENYA: Do Infants Benefit When Older Siblings are Dewormed? (also available in French)
July 2015 Center for Global Development blog post discussion: Mapping the Worm Wars: What the Public Should Take Away from the Scientific Debate about Mass Deworming
October 2014 blog post and video on Africa Can End Poverty: Deworming improves child cognition. Eventually.
Perils of simulation: parallel streams and the case of stata's rnormal command
November 2012 (World Bank WPS 6278); also available from SSRN.
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.
Research in Progress:
Rwanda: Selection and Motivational Impacts of Performance Contracts for Rwandan Primary School Teachers
Joint with Clare Leaver, Pieter Serneels, and Andrew Zeitlin.
Description at World Bank SIEF project page
Description at World Bank REACH grantees page
Kenya: Study of private primary schools and early childhood education centers
Joint with Anthony Keats, Michael Kremer, and Isaac Mbiti.
Description (early childhood) at World Bank ELP countries page
Kenya: EMERGE Reading
Joint with Lia Fernald, Patricia Kariger, Heather Knauer, and Pamela Jakiela.
Description at World Bank ELP countries page
Description at World Bank SIEF project page
Trial Registry ISRCTN68855267