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Using a pair of randomized evaluations, I evaluate a computer assisted learning program designed to reinforce students understanding of material presented in class. The program was implemented in both an in-school and out-of-school model allowing me to assess different strategies for integrating the technology into the existing schools. The effect of the program critically depends on the method of implementation. The program was a poor substitute for the teacher delivered curriculum and as a result, the in-school model caused students to learn significantly less than they otherwise would have learned (-0.57 standard deviations). When implemented as a complement to the normal program in the out-of-school model, however, the program generated average gains of 0.28 standard deviations reflecting small positive (but statistically insignificant) gains by most students and large positive gains by the weakest and older students in the class (from 0.4 to 0.69 standard deviations). The results...
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Working Paper
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June 01, 2008
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Policymakers often prescribe that microfinance institutions increase interest rates to eliminate their reliance on subsidies. This strategy makes sense if the poor are rate insensitive: then microlenders increase profitability (or achieve sustainability) without reducing the poor's access to credit. We test the assumption of price inelastic demand using randomized trials conducted by a consumer lender in South Africa. The demand curves are downward sloping, and steeper for price increases relative to the lender's standard rates. We also find that loan size is far more responsive to changes in loan maturity than to changes in interest rates, which is consistent with binding liquidity constraints.
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Published Paper
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June 01, 2008
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Research has shown that advertising exposure and intensity can impact whether or not a consumer buys a product, but outside the laboratory very little is known about what affect the so-called ‘creative content’ of ads has on consumer demand. Nor do we know much about how important the effect of ad content is relative to that of price. In order to better understand these impacts, researchers developed a field study that varies both advertising content and price in the same setting. This method allows us first toexamine whether ad content affects consumer decisions, then to estimate how much it impacts demand relative to the effect of price. Researchers explore these questions with a South African “cash loan” lender and find that ad content has significant effects on demand, as well as some evidence that the impact of ad content is large relative to that of price.
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Brief
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May 30, 2008
English
Many policymakers advocate heavy subsidies to boost fertilizer use and raise agricultural productivity. In contrast, most economists assume that farmers already take advantage of potential profit opportunities, and argue that heavy subsidies are distortionary, environmentally unsound, regressive, and lead to politicization and inefficiency in fertilizer supply. In earlier work, we show that fertilizer is profitable for farmers in Western Kenya. Yet, usage is low, pointing to possible inefficiencies. In this paper, we build a model with a small fixed cost of purchasing fertilizer in which some farmers are present-biased and partially naïve. Farmers therefore procrastinate, postponing purchasing fertilizer until proceeds from the harvest are spent. Consistent with the model, small time-limited reductions in the cost of purchasing fertilizer at the time of harvest induce substantial increases in fertilizer use, as much as considerably larger price cuts later in the season. Such small time...
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May 01, 2008
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This special issue highlights an empirical approach that has increasingly grown in prominence in the last decade—field experiments. While field experiments can be used quite generally in economics—to test theories’ predictions, to measure key parameters, and to provide insights into the generalizability of empirical results—this special issue focuses on using field experiments to explore questions within the economics of charity. The issuecontains six distinct field experimental studies that investigate various aspects associated with the economics of charitable giving. The issue also includes a fitting tribute to one of the earliest experimenters to depart from traditional lab methods, Peter Bohm, who curiously has not received deep credit or broad acclaim. Hopefully this issue will begin to rectify this oversight.
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Working Paper
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May 01, 2008
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Indoor air pollution (IAP) caused by solid fuel use and/or traditional cooking stoves is a global health threat, particularly for women and young children. The WHO World Health Report 2002 estimates that IAP is responsible for 2.7% of the loss of disability adjusted life years (DALYs) worldwide and 3.7% in high-mortality developing countries. Despite the magnitude of this problem, social scientists have only recently begun to pay closer attention to this issue and to test strategies for reducing IAP. In this paper, we provide a survey of the current literature on the relationship between indoor air pollution, respiratory health and economic well-being. We then discuss the available evidence on the effectiveness of popular policy prescriptions to reduce IAP within the household.
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Working Paper
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February 01, 2008
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In much of the developing world farmers grow crops for local consumption despite export options that appear to be more profitable. This paper reports on a randomized controlled trial conducted by DrumNet in Kenya that attempts to help farmers adopt and market export crops. After one year, DrumNet services led to an increase in production of export crops and lower marketing costs, which translated into household income gains for new adopters. One year after the study, however, the exporter stopped buying from the farmers because they had not become certified to comply with European export requirements. DrumNet collapsed as farmers defaulted on their loans. The risk of such events may explain, at least partly, why many seemingly more profitable export crops are not adopted.   Full published paper is available here.
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Brief
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January 30, 2008
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This study designs a natural field experiment linked to a controlled laboratory experiment to examine the effectiveness of matching gifts and challenge gifts, two popular strategies used to secure a portion of the $200 billion annually given to charities. We find evidence that challenge gifts positively influence contributions in the field, but matching gifts do not. Methodologically, we find important similarities and dissimilarities between behavior in the lab and the field. Overall, our results have clear implications for fundraisers and provide avenues for future empirical and theoretical work on charitable iving.
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January 01, 2008
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The group liability contract feature is often named as key to the growth in lending markets for the poor. Group liability purports to improve repayment rates by providing incentives for peers to screen, monitor and enforce each other’s loans. However, group liability may create excessive pressure and discourage good clients from borrowing, jeopardizing both growth and sustainability. A Philippine bank removed group liability from randomly selected group-screened lending groups. After three years, we find no increase in default and larger groups, thus showing that banks can do just as well as peers at monitoring and enforcing loans and generating high repayment rates.
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Working Paper
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January 01, 2008
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We report results from a randomized evaluation of a merit scholarship program in Kenya in which girls who scored well on academic exams at the end of 6th grade had their school fees paid and received a cash grant for school supplies over the next two years. In the sample as a whole, girls eligible for the scholarship showed substantial gains in academic exam scores, and teacher attendance also improved significantly in program schools. There was also evidence of positive externalities: girls with low pre-test scores, who were unlikely to win scholarships, showed test score gains in program schools. We cannot reject the hypothesis that test score gains were the same for girls with low and high pre-test scores. We see no evidence for weakened intrinsic motivation or gaming, and effects persist after incentives were removed. There is also evidence of heterogeneity in program effects, suggesting the impact of incentives is context dependent. In one of the two study districts, test score ef...
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January 01, 2008
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Social scientists rely heavily on self-reported data. But can respondents be trusted to report the truth? In this paper, the authors compared survey self reports with administrative data and found that nearly 50% of recent borrowers did not report their high-interest consumer loans. Under-reporting appeared to be correlated with several characteristics, in particular gender. Relying strictly on self-reported data may lead to biased inference, and the authors outline some methodological implications for identifying impacts of credit access on borrower behavior and outcomes. Matching female surveyors to female respondents appears to be one low-cost mitigation strategy. The best strategy, however, is to avoid reliance on self-reported data by using lenders’ administrative data or the credit bureau, when feasible.
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Brief
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November 01, 2007
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In stark contrast to bank debt contracts, most micro-finance contracts require that repayments start nearly immediately after loan disbursement and occur weekly thereafter. Even though economic theory suggests that a more flexible repayment schedule would benefit clients and potentially improve their repayment capacity, micro-finance practitioners argue that the fiscal discipline imposed by frequent repayment is critical to preventing loan default. In this paper we use data from a field experiment which randomized client assignment to a weekly or monthly repayment schedule and find no significant effect of type of repayment schedule on client delinquency or default. Our findings suggest that, among micro-finance clients who are willing to borrow at either weekly or monthly repayment schedules, a more flexible schedule can significantly lower transaction costs without increasing client default.
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Working Paper
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November 01, 2007
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We compare survey self-reports with administrative data and find that  50% of recent borrowers do not report their high-interest loans. Under-reporting appears to be correlated with several of interest, in particular gender: 62% of women, when interviewed by men, under-report whereas 42% of women interviewed by women under-report. On the other hand, 40% of men under-report, irrespective of the gender of the interviewer. As such relying strictly on self-reported data may lead to biased inference, and we outline some methodological implications for identifying impacts of credit access on borrower behavior and outcomes. Matching female surveyors to female respondents appears to be a low-cost mitigating strategy, but clearly the best strategy is to make sure one has administrative data from a lender to measure actual borrowing history.    Research brief also available here.
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November 01, 2007
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We use a randomized evaluation of a Kenyan deworming program to estimate peer effects in technology adoption and to shed light on foreign aid donors’ movement towards sustainable community provision of public goods. Deworming is a public good since much of its social benefit comes through reduced disease transmission. People were less likely to take deworming if their direct first-order or indirect second-order social contacts were exposed to deworming. Efforts to replace subsidies with sustainable worm control measures were ineffective: a drug cost-recovery program reduced take-up 80 percent; health education did not affect behavior, and a mobilization intervention failed. At least in this context, it appears unrealistic for a one-time intervention to generate sustainable voluntary local public goods provision.
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August 01, 2007
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The economics literature suggests that enhanced social connection can increase trust amongst agents, which can ultimately lead to more efficient economic outcomes, including increased provision of public goods. This study provides a test of whether social connectedness (proxied via agent similarities in race and gender) influences giving to a charitable fundraiser. Using data gathered from more than 2000 households approached in an actual door-to-door fundraising drive, we find limited evidence of the importance of such social connections. A robust result in the data, however, is that our minority solicitors, whether approaching a majority or minority household, are considerably less likely to obtain a contribution, and conditional on securing a contribution, gift size is lower than their majority counterparts receive.
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August 01, 2007
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The Millennium Development Goals call for reducing by half the proportion of people without sustainable access to safe drinking water. This goal was adopted in large part because clean water was seen as critical to fighting diarrheal disease, which kills 2 million children annually. There is compelling evidence that provision of piped water and sanitation can substantially reduce child mortality. However, in dispersed rural settlements, providing complete piped water and sanitation infrastructure to households is expensive. Many poor countries have therefore focused instead on providing community-level water infrastructure, such as wells. Various traditional child health interventions have been shown to be effective in fighting diarrhea. Among environmental interventions, handwashing and point-of-use water treatment both reduce diarrhea, although more needs to be learned about ways to encourage households to take up these behavior changes. In contrast, there is little evidence that pro...
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May 01, 2007
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Education policy has recently focused on improving accountability and incentives of public providers for actual learning outcomes, often with school-based rewards programs for high performers. The Learning Guarantee Programme in Karnataka, India, is prominent among such efforts, providing cash transfers to government schools that achieve learning at specified high levels. This study examines whether schools that self-selected into the incentive program are different than those that did not. The answer has important implications for how to evaluate the impact of such a program. Although we find no significant differences in resources and characteristics, we do find significant and substantial differences in test scores prior to selection into the program, with better performing schools more likely to opt-in. These findings also provide insight into how incentive-based programs that focus on levels of (rather than changes in) achievement can exacerbate inequality in education. Failing sc...
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April 01, 2007
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To analyze the prospects for expanding financial access to the poor, bank professionals assessed 1,438 households in six provinces in Indonesia to judge their creditworthiness. About 40 percent of poor households were judged creditworthy according to the criteria of Indonesia’s largest microfinance bank, but fewer than 10 percent had recently borrowed from a microbank or formal lender. Possessing collateral appeared as a minor determinant of creditworthiness, in keeping with microfinance innovations. Although these households were judged able to service loans reliably, most desired small loans. Calculations show that the bank, given its current fee structure and banking practices, would lose money when lending at the scales desired. So, while innovations have helped to extend financial access, it remains difficult to lend in small amounts and cover costs
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Brief
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March 01, 2007
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We conducted a natural field experiment to further our understanding of the economics of charity. Using direct mail solicitations to over 50,000 prior donors of a non-profit organization, we tested the effectiveness of a matching grant on charitable giving. We find that the match offer increases both the revenue per solicitation and the response rate. Larger match ratios (i.e., $3:$1 and $2:$1) relative to a smaller match ratio ($1:$1) had no additional impact, however. The results provide avenues for future empirical and theoretical work on charitable giving, costbenefit analysis, and the private provision of public goods.
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January 01, 2007
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This paper uses survey data from 13 countries todocument the economic lives of the poor (those livingon less than $2 dollar per day per capita at purchasingpower parity ) or the extremely poor (those living onless than $1 dollar per day). We describe theirpatterns of consumption and income generation aswell as their access to markets and publicly providedinfrastructure. The paper concludes with a discussionof some apparent anomalous choices.
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Published Paper
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January 01, 2007

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