Evans, David K.
Africa Chief Economist’s Office
Author Name Variants
Fields of Specialization
Education, Social Development
Africa Chief Economist’s Office
Externally Hosted Work
Last updated July 27, 2023
Bio: David is a Lead Economist in the Chief Economist's Office for the Africa Region of the World Bank. He coordinates impact evaluation work across sectors for the Africa Region. In the past, he worked as Senior Economist in the Human Development Department in the Latin America and the Caribbean Region of the World Bank, and as an economist designing and implementing impact evaluations in Africa. He has designed and implemented impact evaluations in agriculture, education, health, and social protection, in Brazil, the Gambia, Kenya, Mexico, Sierra Leone, and Tanzania. He has taught economic development at the Pardee RAND Graduate School of Public Policy, and he holds a Ph.D. in economics from Harvard University.
Publication Search Results
Now showing 1 - 10 of 10
Publication(World Bank, Washington, DC, 2014-05) Evans, David K. ; Popova, AnnaCash transfers have been demonstrated to improve education and health outcomes and alleviate poverty in various contexts. However, policy makers and others often express concern that poor households will use transfers to buy alcohol, tobacco, or other "temptation goods." The income effect of transfers will increase expenditures if alcohol and tobacco are normal goods, but this may be offset by other effects, including the substitution effect, the effect of social messaging about the appropriate use of transfers, and the effect of shifting dynamics in intra-household bargaining. The net effect is ambiguous. This paper reviews 19 studies with quantitative evidence on the impact of cash transfers on temptation goods, as well as 11 studies that surveyed the number of respondents who reported they used transfers for temptation goods. Almost without exception, studies find either no significant impact or a significant negative impact of transfers on temptation goods. In the only (two, non-experimental) studies with positive significant impacts, the magnitude is small. This result is supported by data from Latin America, Africa, and Asia. A growing number of studies from a range of contexts therefore indicate that concerns about the use of cash transfers for alcohol and tobacco consumption are unfounded.
Publication(World Bank Group, Washington, DC, 2014-09) Evans, David K. ; Popova, AnnaAs evidence from rigorous impact evaluations grows in development, there have been more calls to complement impact evaluation analysis with cost analysis, so that policy makers can make investment decisions based on costs as well as impacts. This paper discusses important considerations for implementing cost-effectiveness analysis in the policy making process. The analysis is applied in the context of education interventions, although the findings generalize to other areas. First, the paper demonstrates a systematic method for characterizing the sensitivity of impact estimates. Second, the concept of context-specificity is applied to cost measurement: program costs vary greatly across contexts -- both within and across countries -- and with program complexity. The paper shows how adapting a single cost ingredient across settings dramatically shifts cost-effectiveness measures. Third, the paper provides evidence that interventions with fewer beneficiaries tend to have higher per-beneficiary costs, resulting in potential cost overestimates when extrapolating to large-scale applications. At the same time, recall bias may result in cost underestimates. The paper also discusses other challenges in measuring and extrapolating cost-effectiveness measures. For cost-effectiveness analysis to be useful, policy makers will require detailed, comparable, and timely cost reporting, as well as significant effort to ensure costs are relevant to the local environment.
Publication(World Bank, Washington, DC, 2015-07) Evans, David K. ; Goldstein, Markus ; Popova, AnnaThe ongoing Ebola outbreak in West Africa has put a huge strain on already weak health systems. Ebola deaths have been disproportionately concentrated among health care workers, exacerbating existing skill shortages in Guinea, Liberia, and Sierra Leone in a way that will negatively affect the health of the populations even after Ebola has been eliminated. This paper combines data on cumulative health care worker deaths from Ebola, the stock of health care workers and mortality rates pre-Ebola, and coefficients that summarize the relationship between health care workers in a given country and rates of maternal, infant, and under-five mortality. The paper estimates how the loss of health care workers to Ebola will likely affect non-Ebola mortality even after the disease is eliminated. It then estimates the size of the resource gap that needs to be filled to avoid these deaths, and to reach the minimum thresholds of health coverage described in the Millennium Development Goals. Maternal mortality could increase by 38 percent in Guinea, 74 percent in Sierra Leone, and 111 percent in Liberia due to the reduction in health personnel caused by the epidemic. This translates to an additional 4,022 women dying per year across the three most affected countries. To avoid these deaths, 240 doctors, nurses, and midwives would need to be immediately hired across the three countries. This is a small fraction of the 43,565 doctors, nurses, and midwives that would need to be hired to achieve the adequate health coverage implied by the Millennium Development Goals. Substantial investment in health systems is urgently required not only to improve future epidemic preparedness, but also to limit the secondary health effects of the current epidemic owing to the depletion of the health workforce.
Publication(World Bank Group, Washington, DC, 2015-02) Evans, David K. ; Popova, AnnaThe 2014 Ebola Virus Disease outbreak in West Africa is the largest to date by far. Ebola Virus Disease causes disproportionate mortality among the working-age population, resulting in far more mortality for parents of young children than other health crises. This paper combines data on the age distribution of current and projected mortality from Ebola with the fertility distribution of adults in Guinea, Liberia, and Sierra Leone, to estimate the likely impact of the epidemic on the number of orphans in these three countries. Using the latest mortality estimates (from February 11, 2015), it is estimated that more than 9,600 children have lost one or both parents to Ebola Virus Disease. The absolute numbers of orphans created by the Ebola epidemic are significant, but represent a small fraction (1.4 percent) of the existing orphan burden in the affected countries. Ebola is unlikely to increase the numbers of orphans beyond extended family networks' capacities to absorb them. Nonetheless, the pressures of caring for increased numbers of orphans may result in lower quality of care. These estimates should be used to guide policy to support family networks to improve the capacity to provide high quality care to orphans.
Publication(Elsevier, 2015-07-09) Evans, David K. ; Goldstein, Markus ; Popova, AnnaThe authors modelled how the loss of health-care workers—defined here as doctors, nurses, and midwives—to Ebola might affect maternal, infant, and under-5 mortality in Guinea, Liberia, and Sierra Leone, with the aim of characterising the order of magnitude of likely effects, not providing specific predictions. The authors combined data on: (1) health-care worker deaths from Ebola; (2) the stock of health-care workers pre-Ebola; (3) maternal, infant, and under-5 mortality rates for each country, pre-Ebola; and (4) coefficients of health-care worker mortality, which capture the relation between health-care workers in a given country and different mortality rates (ie, maternal, infant, and under-5 mortality).
What Really Works to Improve Learning in Developing Countries?: An Analysis of Divergent Findings in Systematic Reviews(World Bank Group, Washington, DC, 2015-02) Evans, David K. ; Popova, AnnaIn the past two years alone, at least six systematic reviews or meta-analyses have examined the interventions that improve learning outcomes in low- and middle-income countries. However, these reviews have sometimes reached starkly different conclusions: reviews, in turn, recommend information technology, interventions that provide information about school quality, or even basic infrastructure (such as desks) to achieve the greatest improvements in student learning. This paper demonstrates that these divergent conclusions are largely driven by differences in the samples of research incorporated by each review. The top recommendations in a given review are often driven by the results of evaluations not included in other reviews. Of 227 studies with student learning results, the most inclusive review incorporates less than half of the total studies. Variance in classification also plays a role. Across the reviews, the three classes of programs that are recommended with some consistency (albeit under different names) are pedagogical interventions (including computer-assisted learning) that tailor teaching to student skills; repeated teacher training interventions, often linked to another pedagogical intervention; and improving accountability through contracts or performance incentives, at least in certain contexts. Future reviews will be most useful if they combine narrative review with meta-analysis, conduct more exhaustive searches, and maintain low aggregation of intervention categories.
Publication(World Bank, Washington, DC, 2016-09) Popova, Anna ; Evans, David K. ; Arancibia, VioletaA significant body of research demonstrates that teachers and the quality of their teaching are crucial components of student learning. Many teachers in resource-poor environments have limited knowledge, skills, or motivation. Some impact evaluations have shown promising results from interventions to improve the quality of teaching. This paper reviews the existing body of evidence on what kinds of in-service teacher training interventions are most effective, and highlights the knowledge gaps. It reveals the dearth of detail on the nature of teacher training interventions and proposes a standard set of indicators -- the In-Service Teacher Training Survey Instrument—for reporting on such programs as a prerequisite for understanding which interventions lead to improved student learning. Across a set of 26 programs with impact evaluations and student learning results, programs that provide complementary materials, focus on a specific subject, and include follow-up visits tend to show higher gains. Programs that use non-education professionals as trainers tend to have worse outcomes. Statistical power to identify these effects is limited, and use of these standard indicators in future impact evaluations will facilitate more precise inference.
What Really Works to Improve Learning in Developing Countries?: An Analysis of Divergent Findings in Systematic Reviews(Published by Oxford University Press on behalf of the World Bank, 2016-08) Evans, David K. ; Popova, AnnaOver the course of just two years, at least six reviews have examined interventions that seek to improve learning outcomes in developing countries. Although the reviews ostensibly have the same objective, they reach sometimes starkly different conclusions. The first objective of this paper is to identify why reviews diverge in their conclusions and how future reviews can be more effective. The second objective is to identify areas of overlap in the recommendations of existing reviews of what works to improve learning. This paper demonstrates that divergence in the recommendations of learning reviews is largely driven by differences in the samples of research incorporated in each review. Of 229 studies with student learning results, the most inclusive review incorporates less than half of the total studies. Across the reviews, two classes of programs are recommended with some consistency. Pedagogical interventions that tailor teaching to student learning levels—either teacher-led or facilitated by adaptive learning software—are effective at improving student test scores, as are individualized, repeated teacher training interventions often associated with a specific task or tool. Future reviews will be most useful if they combine narrative review with meta-analysis, conduct more exhaustive searches, and maintain low aggregation of intervention categories.
Publication(World Bank, Washington, DC, 2018-08) Popova, Anna ; Evans, David K. ; Breeding, Mary E. ; Arancibia, Violeta ; Breeding, Mary E.Teachers, like all professionals, require ongoing professional development opportunities to improve their skills. This paper provides evidence on effective professional development characteristics and how at-scale programs incorporate those characteristics. The authors propose a standard set of 70 indicators—the In-Service Teacher Training Survey Instrument—for reporting on professional development programs as a prerequisite for understanding the characteristics of those programs that improve student learning. The authors apply the instrument to rigorously evaluated professional development programs in low- and middle-income countries. Across 33 programs, those programs that link participation to career incentives, have a specific subject focus, incorporate lesson enactment in the training, and include initial face-to-face training tend to show higher student learning gains. In qualitative interviews, program implementers also report follow-up visits as among the most effective characteristics of their professional development programs. The authors then apply the instruments to a sample of 139 government-funded, at-scale professional development programs across 14 countries. This analysis uncovers a sharp gap between the characteristics of teacher professional development programs that evidence suggests are effective and the global realities of most teacher professional development programs.
Publication(Published by Oxford University Press on behalf of the World Bank, 2021-06-04) Popova, Anna ; Evans, David K. ; Breeding, Mary E. ; Arancibia, Violeta ; Breeding, Mary E.Many teachers in low- and middle-income countries lack the skills to teach effectively, and professional development (PD) programs are the principal tool that governments use to upgrade those skills. At the same time, few PD programs are evaluated, and those that are evaluated show highly varying results. This paper proposes a set of indicators—the In-Service Teacher Training Survey Instrument—to standardize reporting on teacher PD programs. An application of the instrument to 33 rigorously evaluated PD programs shows that programs that link participation to career incentives, have a specific subject focus, incorporate lesson enactment in the training, and include initial face-to-face training tend to show higher student learning gains. In qualitative interviews, program implementers also report follow-up visits as among the most effective characteristics of their professional development programs. This paper then uses the instrument to present novel data on a sample of 139 government-funded, at-scale professional development programs across 14 countries. The attributes of most at-scale teacher professional development programs differ sharply from those of programs that evidence suggests are effective, with fewer incentives to participate in PD, fewer opportunities to practice new skills, and less follow-up once teachers return to their classrooms.