Papers - Natural

Paul Glewwe, Michael Kremer, Sylvie Moulin, Eric Zitzewitz

Cited by*: 42 Downloads*: 16

This paper compares retrospective and prospective analyses of the effect of flip charts on test scores in rural Kenyan schools. Retrospective estimates that focus on subjects for which flip charts are used suggest that flip charts raise test scores by up to 20 percent of a standard deviation. Controlling for other educational inputs does not reduce this estimate. In contrast, prospective estimators based on a study of 178 schools, half of which were randomly selected to receive charts, provide no evidence that flip charts increase test scores. One interpretation is that the retrospective results were subject to omitted variable bias despite the inclusion of control variables. If the direction of omitted variable bias were similar in other retrospective analyses of educational inputs in developing countries, the effects of inputs may be even more modest than retrospective studies suggest. Bias appears to be reduced by a differences-in-differences estimator that examines the impact of flip charts on the relative performance of students in flip chart and other subjects across schools with and without flip charts, but it is not clear that this approach is applicable more generally.

Dean S Karlan, Jonathan Zinman

Cited by*: 4 Downloads*: 16

The price elasticity of demand for credit has major implications for macroeconomics, finance, and development. We present estimates of this parameter derived from a randomized trial. The experiment was implemented by a consumer microfinance lender in South Africa and identifies demand curves that, while downward-sloping with respect to price, are flatter than recent estimates in both developing and developed countries throughout most of a wide price range. However, demand becomes highly price sensitive at higher-than-normal rates. We discuss several interpretations of this kink and present some related evidence. We also find that loan size is far more responsive to changes in loan maturity than to changes in interest rate. This pattern is more pronounced among lower income individuals, a comparative static that has been observed in the United States as well and is consistent with liquidity constraints that decrease with income.

Paul W Rhode, Koleman S Strumpf

Cited by*: 12 Downloads*: 16

Political stock markets have a long history in the United States. Organized prediction markets for Presidential elections have operated on Wall Street (1880-1944), the Iowa Electronic Market (1988-present), and TradeSports (2001-present). Proponents claim such markets efficiently aggregate information and provide forecasts superior to polls. An important counterclaim is that such markets may be subject to manipulation by interested parties. We analyze this argument by studying alleged and actual speculative attacks- large trades, uninformed by fundamentals, intended to change prices- in these three markets. We first examine the historical Wall Street markets where political operatives from the contending parties actively and openly bet on city, state and national races; the record is rife with accusations that parties tried to boost their candidates through investments and wash bets. Next we report the results of a field experiment involving a series of planned, random investments-- accounting for two percent of total market volume-- in the Iowa Electronic Market in 2000. Finally, we investigate the speculative attacks on TradeSports market in 2004 when a single trader made a series of large investments in an apparent attempt to make one candidate appear stronger. In the cases studied here, the speculative attack initially moved prices, but these changes were quickly undone and prices returned close to their previous levels. We find little evidence that political stock markets can be systematically manipulated beyond short time periods.

Peggy Dwyer , James Gilkeson , John A List

Cited by*: 46 Downloads*: 15

Using data from a national survey of nearly 2000 mutual fund investors, we investigate whether investor gender is related to risk taking as revealed in mutual fund investment decisions. Consonant with the received literature, we find that women exhibit less risk-taking than men in their most recent, largest, and riskiest mutual fund investment decisions. More importantly, we find that the impact of gender on risk taking is significantly weakened when investor knowledge of financial markets and investments is controlled in the regression equation. This result suggests that the greater level of risk aversion among women that is frequently documented in the literature can be substantially, but not completely, explained by knowledge disparities.

Andries de Grip, Jan Sauermann

Cited by*: 0 Downloads*: 14

This paper analyses the effects of work-related training on worker productivity. To identify the causal effects from training, we combine a field experiment that randomly assigns workers to treatment and control groups with panel data on individual worker performance before and after training. We find that participation in the training programme leads to a 10 percent increase in performance. Moreover, we provide experimental evidence for externalities from treated workers on their untreated teammates: An increase of 10 percentage points in the share of treated peers leads to a performance increase of 0.51 percent. We provide evidence that the estimated effects are causal and not the result of employee selection into and out of training. Furthermore, we find that the performance increase is not due to lower quality provided by the worker.

John A List, Anya Samek

Cited by*: 2 Downloads*: 14

Almost a third of US children ages 2-19 are deemed overweight or obese, and part of the problem is the habitual decision to consume high calorie, low nutrient foods. We propose that the school lunchroom provides a 'teachable moment' to engage children in making healthful choices. We conduct a field experiment with over 1,500 participants in grades K-8 and evaluate the impact of small non-monetary incentives on the selection of milk in the school lunchroom. At baseline, only 16% of children select white milk relative to 84% choosing chocolate milk. We find a significant effect of incentives, which increase white milk selection by 2.5 times, to 40%. One concern with incentives is that they may decrease intrinsic motivation to eat healthy, called 'crowd-out of intrinsic motivation.' However, we do not find evidence of 'crowd-out'; rather, we see some suggestive evidence of the positive habit forming effect of incentives.

John A List

Cited by*: 21 Downloads*: 14

Walrasian tatonnement has been a fundamental assumption in economics ever since Walrasian general equilibrium theory was introduced in 1874. Nearly a century after its introduction, Vernon Smith relaxed the Walrasian tatonnement assumption by showing that neoclassical competitive market theory explains the equilibrating forces in double-auction markets. I make a next step in this evolution by exploring the predictive power of neoclassical theory in decentralized naturally occurring markets. Using data gathered from two distinct markets--the sports card and collector pin markets--I find a tendency for exchange prices to approach the neoclassical competitive model prediction after a few market periods.

John A List, Robert D Metcalfe

Cited by*: 3 Downloads*: 14

Field experiments represent a relatively new area in economics to understand the causal links from one variable to another. They have been used by academics to help answer interesting and policy-relevant questions in the developed world relating to educational attainment, tax avoidance, consumer finance, negative externalities, charitable giving, and labour market contracts. In this paper we bring together the key ideas behind the different variants of field experiments, how field experiments have been used to test theory, their limitations, and the new areas currently being opened up by field experiments.

Marianne Bertrand, Simeon Djankov, Rema Hanna, Sendhil Mullainathan

Cited by*: 9 Downloads*: 14

We follow 822 applicants through the process of obtaining a driver's license in New Delhi, India. To understand how the bureaucracy responds to individual and social needs, participants were randomly assigned to one of three groups: bonus, lesson, and comparison groups. Participants in the bonus group were offered a financial reward if they could obtain their license fast; participants in the lesson group were offered free driving lessons. To gauge driving skills, we performed a surprise driving test after participants had obtained their licenses. Several interesting facts regarding corruption emerge. First, the bureaucracy responds to individual needs. Those who want their license faster (e.g. the bonus group), get it 40% faster and at a 20% higher rate. Second, the bureaucracy is insensitive to social needs. The bonus group does not learn to drive safely in order to obtain their license: in fact, 69% of them were rated as "failures" on the independent driving test. Those in the lesson group, despite superior driving skills, are only slightly more likely to obtain a license than the comparison group and far less likely (by 29 percentage points) than the bonus group. Detailed surveys allow us to document the mechanisms of corruption. We find that bureaucrats arbitrarily fail drivers at a high rate during the driving exam, irrespective of their ability to drive. To overcome this, individuals pay informal "agents" to bribe the bureaucrat and avoid taking the exam altogether. An audit study of agents further highlights the insensitivity of agents' pricing to driving skills. Together, these results suggest that bureaucrats raise red tape to extract bribes and that this corruption undermines the very purpose of regulation.

Orana Bandiera, Iwan Barankay, Imran Rasul

Cited by*: 4 Downloads*: 14

We document the establishment and evolution of a cooperative norm among workers using evidence from a natural field experiment on a leading UK farm. Workers are paid according to a relative incentive scheme under which increasing individual effort raises a worker's own pay but imposes a negative externality on the pay of all co-workers, thus creating a rationale for cooperation. As a counterfactual, we analyze worker behavior when workers are paid piece rates and thus have no incentive to cooperate. We find that workers cooperate more as their exposure to the relative incentive scheme increases. We also find that individual and group exposure are substitutes, namely workers who work alongside colleagues with higher exposure cooperate more. Shocks to the workforce in the form of new worker arrivals disrupt cooperation in the short term but are then quickly integrated into the norm. Individual exposure, group exposure, and the arrival of new workers have no effect on productivity when workers and paid piece rates and there is no incentive to cooperate.

Ryan D Friedrichs

Cited by*: 0 Downloads*: 14

No abstract available

Jan Hansen, Carsten Schmidt, Martin Strobel

Cited by*: 6 Downloads*: 13

Political stock markets (PSM) are sometimes seen as substitutes for opinion polls. On the bases of a behavioural model, specific preconditions were drawn out under which manipulation in PSM can weaken this argument. Evidence for manipulation is reported from the data of two separate PSM during the Berlin 1999 state elections.

Michael Kremer, Edward Miguel, Rebecca Thornton

Cited by*: 16 Downloads*: 13

We report results from a randomized evaluation of a merit scholarship program for adolescent girls in Kenya. Girls who scored well on academic exams had their school fees paid and received a cash grant for school supplies. Girls eligible for the scholarship showed significant gains in academic exam scores (average gain 0.12-0.19 standard deviations) and these gains persisted following the competition. There is also evidence of positive program externalities on learning: boys, who were ineligible for the awards, also showed sizeable average test gains, as did girls with low pretest scores, who were unlikely to win. Both student and teacher school attendance increased in the program schools. We discuss implications both for understanding the nature of educational production functions and for the policy debate surrounding merit scholarships.

John Gibson, David McKenzie, Steven Stillman

Cited by*: 3 Downloads*: 13

People migrate to improve their well-being, whether through an expansion of economic and social opportunities or a reduction in persecution. Yet a large literature suggests that migration can be a very stressful process, with potentially negative impacts on mental health reducing the net benefits of migration. However, to truly understand the effect of migration on mental health one must compare the mental health of migrants to what their mental health would have been had they stayed in their home country. The existing literature is not able to do this and typically settles for comparing the mental health of migrants to that of natives in the destination country, which takes no account of any pre-existing differences between these groups. This paper overcomes the selection problems affecting previous studies of the effect of migration on mental health by examining a migrant lottery program. New Zealand allows a quota of Tongans to immigrate each year with a lottery used to choose amongst the excess number of applicants. A unique survey conducted by the authors in these two countries allows experimental estimates of the mental health effects of migration to be obtained by comparing the mental health of migrants who were successful applicants in the lottery to the mental health of those who applied to migrate under the quota, but whose names were not drawn in the lottery. Migration is found to lead to improvements in mental health, particularly for women and those with poor mental health in their home country.

Rama Katkar, David Lucking-Reiley

Cited by*: 7 Downloads*: 13

Sellers in eBay auctions have the opportunity to choose both a public minimum bid amount and a secret reserve price. We ask, empirically, whether the seller is made better or worse off by setting a secret reserve above a low minimum bid, versus the option of making the reserve public by using it as the minimum bid level. In a field experiment, we auction 50 matched pairs of Pokemon cards on eBay, half with secret reserves and half with equivalently high public minimum bids. We find that secret reserve prices make us worse off as sellers, by reducing the probability of the auction resulting in a sale, deterring serious bidders from entering the auction, and lowering the expected transaction price of the auction. We also present evidence that some sellers choose to use secret reserve prices for reasons other than increasing their expected auction prices.

Daron Acemoglu, David Laibson , John A List

Cited by*: 4 Downloads*: 13

Internet-based educational resources are proliferating rapidly. One concern associated with these (potentially transformative) technological changes is that they will be disequalizing - as many technologies of the last several decades have been - creating superstar teachers and a winner-take-all education system. These important concerns notwithstanding, we contend that a major impact of web-based educational technologies will be the democratization of education: educational resources will be more equally distributed, and lower-skilled teachers will benefit. At the root of our results is the observation that skilled lecturers can only exploit their comparative advantage if other teachers complement those lectures with face-to-face instruction. This complementarity will increase the quantity and quality of face-to-face teaching services, potentially increasing the marginal product and wages of lower-skill teachers.

Catherine Co , John A List

Cited by*: 47 Downloads*: 13

This paper employs a conditional logit model to estimate the effects of state environmental regulations on foreign multinational corporations' new plant location decisions from 1986 to 1993. The relationship between site choice and state environmental regulations is explored, using four measures of regulatory stringency. We find evidence that heterogeneous environmental policies across states do matter.

Alan S Gerber, Donald P Green

Cited by*: 12 Downloads*: 13

No abstract available

Michael Kremer, Edward Miguel

Cited by*: 7 Downloads*: 13

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.

Kenneth Leonard, Melkiory Masatu

Cited by*: 0 Downloads*: 12

The most important issue facing experimental economists is the generalizability of lab results. This letter examines more than 1200 doctor/patient consultations, in which scrutiny and duration of treatment were varied. We show that scrutiny has an important but short-lived effect.