Dean Karlan

Northwestern University | NU · Department of Finance

We study the impact of group-based cognitive behavioral therapy (CBT ) for individuals selected from the general population of poor households in rural Ghana (N = 7,227). Results from one to three months after the program show strong impacts on mental and perceived physical health, cognitive and socioemotional skills, and economic self-perceptions....

Many policies attempt to help extremely poor households build sustainable sources of income. Although economic interventions have predominated historically1,2, psychosocial support has attracted substantial interest3–5, particularly for its potential cost-effectiveness. Recent evidence has shown that multi-faceted ‘graduation’ programmes can succee...

Asbtract The COVID-19 pandemic has devastated many low- and middle-income countries, causing widespread food insecurity and a sharp decline in living standards ¹ . In response to this crisis, governments and humanitarian organizations worldwide have distributed social assistance to more than 1.5 billion people ² . Targeting is a central challenge i...

Classic theories suggest that common pool resources are subject to overexploitation. Community-based resource management approaches may ameliorate tragedy of the commons effects. Here we use a randomized evaluation in Namibia’s communal rangelands to study a comprehensive four-year program to support community-based rangeland and cattle management....

Significance Encouraging vaccination is a pressing policy problem. Our megastudy with 689,693 Walmart pharmacy customers demonstrates that text-based reminders can encourage pharmacy vaccination and establishes what kinds of messages work best. We tested 22 different text reminders using a variety of different behavioral science principles to nudge...

Policy-makers are increasingly turning to behavioural science for insights about how to improve citizens’ decisions and outcomes¹. Typically, different scientists test different intervention ideas in different samples using different outcomes over different time intervals². The lack of comparability of such individual investigations limits their po...

A multi-faceted program comprising a grant of productive assets, training, unconditional cash transfers, coaching, and savings has been found to build sustainable income for those in extreme poverty. We focus on two important questions: whether a mere grant of productive assets would generate similar impacts (it does not), and whether access to a s...

Markets for consumer financial services are growing rapidly in low- and middle-income countries and are being transformed by digital technologies and platforms. With growth and change come concerns about protecting consumers from firm exploitation due to imperfect information and contracting as well as from their own decision-making limitations. We...

Social protection programs are needed more than ever during periods of social upheaval, but are also likely to be even harder to implement successfully. Furthermore, social upheaval makes measuring the impact of such policies all the more difficult. We study the impact of a multi-faceted social protection program, often referred to as a “graduation...

Two for‐profit Philippine banks, aiming to increasing microlending to the poor, incorporated a widely used poverty measurement tool into their loan applications and tested the tool using randomized training content. Treated loan officers were provided an explanation of the tool's purpose; exhortation tying the tool to the organizations' social miss...

Widespread acceptance of COVID-19 vaccines is crucial for achieving sufficient immunization coverage to end the global pandemic, yet few studies have investigated COVID-19 vaccination attitudes in lower-income countries, where large-scale vaccination is just beginning. We analyze COVID-19 vaccine acceptance across 15 survey samples covering 10 low-...

Ethics in social science experimentation and data collection are often discussed but rarely articulated in writing as part of research outputs. Although papers typically reference human subjects research approvals from relevant institutional review boards, most recognize that such boards do not carry out comprehensive ethical assessments. We propos...

Many Americans fail to get life-saving vaccines each year, and the availability of a vaccine for COVID-19 makes the challenge of encouraging vaccination more urgent than ever. We present a large field experiment ( N = 47,306) testing 19 nudges delivered to patients via text message and designed to boost adoption of the influenza vaccine. Our findin...

Introduction: We evaluate whether a combination of financial incentives and deposit contracts improves cessation rates among low- to moderate-income smokers. Methods: We randomly assigned 311 smokers covered by Medicaid at 12 health clinics in Connecticut to usual care or one of the three treatment arms. Each treatment arm received financial inc...

Classic theories suggest that common pool resources are subject to overexploitation. Community-based resource management approaches may ameliorate “tragedy of the commons” effects. Using a randomized evaluation in Namibia’s communal rangelands, we find that a comprehensive four-year program to support community-based rangeland and cattle management...

Background As vaccination campaigns are deployed worldwide, addressing vaccine hesitancy is of critical importance to ensure sufficient immunization coverage. We analyzed COVID-19 vaccine acceptance across 15 samples covering ten low- and middle- income countries (LMICs) in Asia, Africa, and South America, and two higher income countries (Russia an...

Despite numerous journalistic accounts, systematic quantitative evidence on economic conditions during the ongoing COVID-19 pandemic remains scarce for most low- and middle-income countries, partly due to limitations of official economic statistics in environments with large informal sectors and subsistence agriculture. We assemble evidence from ov...

We conducted a fundraising experiment with an international development nonprofit organization in which a matching grant offered by the Bill and Melinda Gates Foundation raised more funds than one from an anonymous donor. The effect is strongest for solicitees who previously gave to other BMGF-supported, poverty charities. With supporting evidence...

We test whether the endowment effect holds in an experiment conducted with children during Halloween trick-or-treating. We do not find evidence of the endowment effect in this context and with this experimental protocol.

We study the causal impact of religiosity through a randomized evaluation of an evangelical Protestant Christian values and theology education program delivered to thousands of ultrapoor Filipino households. Six months after the program ended, treated households have higher religiosity and income; no statistically significant differences in total l...

Low utilization of household credit in developing countries may be partially due to religious considerations. In a randomized marketing experiment in Jordan, this paper estimates the effect of sharia-compliant loan features on demand for credit. To comply with Islamic law, the sharia-compliant product uses a bank fee rather than an interest payment...

Causal inference lies at the heart of social science, and the 2019 Nobel Prize in Economics highlights the value of randomized variation for identifying causal effects and mechanisms. But causal inference cannot rely on randomized variation alone; it also requires good data. Yet the data-generating process has received less consideration from econo...

In this blog post originally published on the World Bank Development Impact blog, BITSS and the JDE Editorial Team reflect on lessons learned from the first year of pre-results review and offer perspectives on the future of pre-results review at the JDE and in the discipline as a whole. Given the high interest among authors and the largely positive...

In a new effort to potentially help address this problem, the Journal of Development Economics (JDE) now offers authors the opportunity to have their prospective empirical projects reviewed and approved for publication before the results are known. This track for article submissions will be available as part of a pilot project, which will allow us...

This study reports results from a randomized evaluation of a mandatory six-month Internet-based sexual education course implemented across public junior high schools in 21 Colombian cities. Six months after finishing the course, the study finds a 0.4 standard deviation improvement in knowledge, a 0.2 standard deviation improvement in attitudes, and...

We use randomized interest rates, offered across eighty geographically distinct regions for twenty-nine months by Mexico’s largest microlender, to sketch the adjustment from a price change to a new equilibrium. Demand is elastic, and more so over the longer run; e.g. the dollars-borrowed elasticity increases from $-$1.1 in Year one to $-$2.9 in Yea...

A debt trap occurs when someone takes on a high-interest-rate loan and is barely able to pay back the interest, and thus perpetually finds themselves in debt (often by refinancing). Studying such practices is important for understanding financial decision-making of households in dire circumstances, and also for setting appropriate consumer protecti...

This chapter details a study conducted with Opportunity International Savings and Loans, Ltd. (OISL)—one of Ghana's largest microfinance institutions—which analyzes the implications of interest rate for both revenue and outreach. The basic concept was simple: market loans to different people using a range of interest rates and observe how many and...

This chapter looks at the challenges that arise from working with partner organizations. Evaluations provide evidence about effectiveness and impact, and offer operational insights that can spur improvements to products and processes. From a researcher's perspective, partnerships with practitioners offer access to the people who live and breathe th...

This chapter focuses on low participation rates. Low participation rates squeeze the effective sample size for a test, making it more difficult, statistically, to identify a positive treatment effect. There are two moments in which low participation rates can materialize: during the intake process to a study or intervention, or after random assignm...

This introductory chapter provides an overview of the growth of randomized controlled trials (RCTs). RCTs found their way into domestic social policy discussions as early as the 1960s when they were used to evaluate government assistance programs, such as negative income tax rates for the poor. In the 1990s, a new crop of development economists beg...

This chapter assesses a study conducted with SKS Microfinance and insurer ICICI-Lombard where the researchers added a mandatory health insurance policy to SKS microloans to test the theory that bundling policies with other products creates a viable pool of clients for insurers. SKS's bundling of insurance with microloans proved so problematic that,...

All across the social sciences, from development economics to political science departments, researchers are going into the field to collect data and learn about the world. While much has been gained from the successes of randomized controlled trials, stories of failed projects often do not get told. This book delves into the common causes of failu...

This chapter examines technical design flaws. There are two common issues to avoid when it comes to survey design: bloated surveys, particularly without a clear analysis plan for all questions; and poorly designed survey items. No less important than the survey and other data collection tools is the plan to deploy them. As such, researchers should...

This chapter assesses survey and measurement execution problems in field research. Until recently, the vast majority of surveys in development field studies were done the old-fashioned way, on clipboards with pen and paper. The past five years have seen a huge shift toward electronic data collection using laptops, personal digital assistants (PDAs)...

This chapter examines a study conducted with the Peruvian microfinance institution Arariwa, which explores a number of questions regarding technology's potential and proper role as a development tool by implementing and testing a multimedia financial education program for clients. In this case, there are two major areas of failures: research settin...

This chapter focuses on a study which assesses two sets of policy levers that can be pushed to increase savings: improving the accounts people can access and encouraging people to save more. The researchers worked with local partner organizations on two interventions: a simple group-based savings account and a youth-focused financial literacy curri...

This concluding chapter offers some guide on how to run a field study. First, researchers should think about where, when, and with whom they will run their experiment, and make sure these parameters fit the underlying idea or theory they intend to test. Second, every question in a survey should have a purpose. Researchers should be mindful that sub...

This chapter examines a study conducted by a microfinance institution (MFI) where they began developing educational supplements for their client base of poor women on the topics of infant/child health and business training. With tailored materials ready, the MFI launched the program in about half of its branches, using an “integrated model” in whic...

This chapter looks at the Poultry Loan, a credit-to-savings intervention. Through an informational and promotional campaign, the researchers recruited fifty participants willing to try poultry farming and launched a pilot. At this stage the research did not include an impact evaluation but just sought to determine whether the model was operationall...

This chapter discusses inappropriate research setting. In practice, choosing a setting is often a complex process. It takes time and effort, judgment, and a theory that describes how the underlying context will interact with the treatment to be tested. Problems often arise when researchers try to shoehorn a fit. A few common pitfalls worth mentioni...

Experts bring economic tools to bear on philanthropic activities, addressing topics that range from the determinants of giving to the effectiveness of fundraising techniques. Economists are increasingly aware of the need to better understand philanthropic activities. In this book, economists address a variety of topics related to the economics of p...

The way in which a product is distributed can have lasting effects on demand by influencing learning, anchoring price expectations, and shaping perceptions of product value. While these issues apply broadly, they are particularly important for health products in poor countries, where short-term subsidies are common, similar products are often avail...

Background: HIV infection has profound clinical and economic costs at the household level. This is particularly important in low-income settings, where access to additional sources of income or loans may be limited. While several microfinance interventions have been proposed, unconditional cash grants, a strategy to allow participants to choose ho...

We experimentally test the impact of expanding access to basic bank accounts in Uganda, Malawi, and Chile. Over two years, 17, 10, and 3 percent of treatment individuals made five or more deposits, respectively. Average monthly deposits in treatment accounts were sizable among users, corresponding to the seventy-ninth, ninety-first, and ninety-sixt...

This paper argues that firms use referrals from current workers to mitigate a moral hazard problem. I develop a model in which referrals relax a limited liability con-straint by allowing the firm to punish both the referral recipient and referral provider if the recipient has low output. This punishment implies that there is positive correla-tion b...

Governments and non-governmental organizations promote school-based financial literacy programs as means to instill financial behaviors that can persist through adulthood. We conduct a randomized trial of two financial literacy education programs in government-run Ghanaian primary and junior high schools. The first integrated both financial and soc...

Objective To evaluate the microfoundations of a personality-inspired public health campaign’s influence on minors. Design Multi-year randomized control trial. Setting Economics professor’s front porch in New Haven, CT. Participants 1223 trick-or-treaters in New Haven over three years; on average, 8.5 years old and 53% male (among children whose...

Disaggregation of data. (DOCX)

We study the causal impact of religiosity through a randomized evaluation of an evangelical Protestant Christian values and theology education program delivered to thousands of ultrapoor Filipino households. Six months after the program ended, treated households have higher religiosity and income; no statistically significant differences in total l...

Nonprofits, governments, and social enterprises face increasing pressure to prove that their programs are making a positive impact on the world. This focus on impact is positive: learning whether we are making a difference enhances our ability to effectively address pressing social problems, and is critical for wise stewardship of resources. Howeve...

A randomized control trial with 432 small and medium enterprises in Mexico shows positive impact of access to 1 year of management consulting services on total factor productivity and return on assets. Owners also had an increase in “entrepreneurial spirit” (an index that measures entrepreneurial confidence and goal setting). Using Mexican social s...

Lower prices produce higher demand… or do they? A bank's direct marketing to holders of “free” checking accounts shows that a large discount on 60% APR overdrafts reduces overdraft usage, especially when bundled with a discount on debit card or auto-debit transactions. In contrast, messages mentioning overdraft availability without mentioning price...

A Philippine bank tested sensitivity to interest rates and account ownership requirements in 10,000 randomized door-to-door solicitations for a commitment savings account. Take-up is substantial (23%), but price elasticity of saving in this account is not significantly different from zero in either the full sample or sub-groups of plausibly margina...