Research Topics

EPAR Technical Report #354
Publication Date: 11/29/2018
Type: Research Brief
Abstract

Precise agricultural statistics are necessary to track productivity and design sound agricultural policies. Yet, in settings where intercropping is prevalent, even crop yield can be challenging to measure. In a systematic survey of the literature on crop yield in low-income settings, we find that scholars specify how they estimate the yield denominator in under 10% of cases. Using household survey data from Tanzania, we consider four alternative methods of allocating land area on plots that contain multiple crops, and explore the implications of this measurement decision for analyses of maize and rice yield. We find that 64% of cultivated plots contain more than one crop, and average yield estimates vary with different methods of calculating area planted. This pattern is more pronounced for maize, which is more likely than rice to share a plot with other crops. The choice among area methods influences which of these two staple crops is found to be more calorie-productive per ha, as well as the extent to which fertilizer is expected to be profitable for maize production. Given that construction decisions can influence the results of analysis, we conclude that the literature would benefit from greater clarity regarding how yield is measured across studies.

EPAR Technical Report #359
Publication Date: 11/13/2017
Type: Literature Review
Abstract

Cash transfer programs are interventions that directly provide cash to target specific populations with the aim of reducing poverty and supporting a variety of development outcomes. Low- and middle-income countries have increasingly adopted cash transfer programs as central elements of their poverty reduction and social protection strategies. Bastagli et al. (2016) report that around 130 low- and middle-income countries have at least one UCT program, and 63 countries have at least one CCT program (up from 27 countries in 2008). Through a comprehensive review of literature, this report primarily considers the evidence of the long-term impacts of cash transfer programs in low- and lower middle-income countries. A review of 54 reviews that aggregate and summarize findings from multiple studies of cash transfer programs reveals largely positive evidence on long-term outcomes related to general health, reproductive health, nutrition, labor markets, poverty, and gender and intra-household dynamics, though findings vary by context and in many cases overall conclusions on the long-term impacts of cash transfers are mixed. In addition, evidence on long-term impacts for many outcome measures is limited, and few studies explicitly aim to measure long-term impacts distinctly from immediate or short-term impacts of cash transfers.

EPAR Research Brief #344
Publication Date: 08/10/2016
Type: Research Brief
Abstract

This brief presents an overview of EPAR’s previous research related to gender. We first present our key takeaways related to labor and time use, technology adoption, agricultural production, control over income and assets, health and nutrition, and data collection. We then provide a brief overview of each previous research project related to gender along with gender-related findings, starting with the most recent project. Many of the gender-related findings draw from other sources; please see the full documents for references. Reports available on EPAR’s website are hyperlinked in the full brief. 

EPAR Research Brief #332
Publication Date: 02/26/2016
Type: Literature Review
Abstract

Household survey data are a key source of information for policy-makers at all levels. In developing countries, household data are commonly used to target interventions and evaluate progress towards development goals. The World Bank’s Living Standards Measurement Study - Integrated Surveys on Agriculture (LSMS-ISA) are a particularly rich source of nationally-representative panel data for six Sub-Saharan African countries: Ethiopia, Malawi, Niger, Nigeria, Tanzania, and Uganda. To help understand how these data are used, EPAR reviewed the existing literature referencing the LSMS-ISA and identified 415 publications, working papers, reports, and presentations with primary research based on LSMS-ISA data. We find that use of the LSMS-ISA has been increasing each year since the first survey waves were made available in 2009, with several universities, multilateral organizations, government offices, and research groups across the globe using the data to answer questions on agricultural productivity, farm management, poverty and welfare, nutrition, and several other topics.

EPAR Research Brief #321
Publication Date: 01/29/2016
Type: Literature Review
Abstract

Agricultural productivity growth has been empirically linked to poverty reduction across a range of measures for both staple and export crops. Many public and private organizations have thus made it a priority to increase farm productivity, and have invested billions toward this end.This report compiles measures commonly used to track agricultural productivity and discusses the ways in which they are subject to error, bias, and other data limitations. Though each measure has limitations, choosing the measure(s) most appropriate to the goals of an analysis and understanding the sources of variation allows for more effective and closely targeted investments and policy and program recommendations, particularly when measures suggest different drivers of productivity growth and links to poverty reduction. 

EPAR Research Brief #318
Publication Date: 01/29/2016
Type: Research Brief
Abstract

This brief summarizes the evidence base for various types of commonly-used time use measurements, lists categories of time use as identified by major organizations and reports, and identifies studies finding significant impacts of interventions designed to reduce specific time constraints. The various approaches to time use measurement method each have different limitations (cost, timing, seasonality, susceptibility to recall bias, etc.), which may have implications for data analysis. The choice of how to measure time use may be particularly important for analyzing women’s time use. For example, limiting respondents to one activity per time slot when measuring daily time allocation may underestimate women's productivity or time allocations, as they are more likely than men to conduct simultaneous activities, such as childcare along with other activities.

EPAR Technical Report #310
Publication Date: 11/20/2015
Type: Literature Review
Abstract

Cereal yield variability is influenced by initial conditions such as suitability of the farming system for cereal cultivation, current production quantities and yields, and zone-specific potential yields limited by water availability. However, exogenous factors such as national policies, climate, and international market conditions also impact farm-level yields directly or provide incentives or disincentives for farmers to intensify production. We conduct a selective literature review of policy-related drivers of maize yields in Ethiopia, Kenya, Malawi, Rwanda, Tanzania, and Uganda and pair the findings with FAOSTAT data on yield and productivity. This report presents our cumulative findings along with contextual evidence of the hypothesized drivers behind maize yield trends over the past 20 years for the focus countries.

EPAR Research Brief #312
Publication Date: 07/30/2015
Type: Literature Review
Abstract

This brief reviews the evidence of realized yield gains by smallholder farmers attributable to the use of high-quality seed and/or improved seed varieties. Our analysis suggests that in most cases, use of improved varieties and/or quality seed is associated with modest yield increases.  In the sample of 395 trials reviewed, positive yield changes accompanied the use of improved variety or quality seed, on average, in 10 out of 12 crops, with rice and cassava as the two exceptions.

EPAR Technical Report #298
Publication Date: 03/23/2015
Type: Literature Review
Abstract

Cassava production is prone to many constraints throughout the production cycle, including biotic, abiotic, and management constraints. This brief reviews the literature on the production impacts of two key cassava stressors: cassava bacterial blight (CBB) and postharvest physiological deterioration (PPD). We summarize available estimates of the frequency and magnitude of these constraints relative to other drivers of cassava production losses that affect smallholder farmers in Sub-Saharan Africa (SSA), review the control strategies proposed in the literature, report on the views of several experts in the field, and identify research gaps where relatively little appears to be known about CBB or PPD yield impacts or best practices for CBB or PPD management. 

EPAR Research Brief #228
Publication Date: 04/18/2014
Type: Literature Review
Abstract

Cassava (Manihot esculenta Crantz) is a widely-grown staple food in the tropical and subtropical regions of Africa, Asia, and Latin America. In this brief we examine the environmental constraints to, and impacts of, smallholder cassava production systems in Sub-Saharan Africa (SSA) and South Asia (SA), noting where the analysis applies to only one of these regions. We highlight crop-environment interactions at three stages of the cassava value chain: pre-production (e.g., land clearing), production (e.g., soil, water, and input use), and post-production (e.g., crop storage). At each stage we emphasize environmental constraints on production (poor soil quality, water scarcity, crop pests, etc.) and also environmental impacts of crop production (e.g., soil erosion, water depletion and pesticide contamination). We then highlight good practices for overcoming environmental constraints and minimizing environmental impacts in smallholder cassava production systems. Evidence on environmental issues in smallholder cassava production is relatively thin, and unevenly distributed across regions. The literature on cassava in South Asian smallholder systems is limited, reflecting a crop of secondary importance (though it is widely found elsewhere in Asia such as South East Asia), in comparison to cassava in much of SSA. The majority of the research summarized in this brief is from SSA. The last row of Table 1 summarizes good practices currently identified in the literature. However, the appropriate strategy in a given situation will vary widely based on contextual factors, such as local environmental conditions, market access, cultural preferences, production practices and the policy environment.