DEVELOPMENT
EVIDENCE

Making evidence accessible

Photo: Navishti Das, Dharamshala, Himachal Pradesh, India, July 2018

WHY DEVIDENCE

Researchers in international development have run thousands of studies estimating the causal impact of social programs in low- and middle-income countries. Each one produces survey data, results, and documentation. But without common organization and structure, aggregation is challenging and limits use for the next researcher, funder, or implementer who wants to know what works across studies, under what conditions and for whom. The high cost of synthesizing data leads to underutilization of evidence in policymaking, resulting in millions of missed opportunities to do the most we can to alleviate societal problems.

DEVIDENCE is an initiative to build comprehensive, open-access data that makes evidence aggregation cheaper and easier. It builds the open-source pipelines, standards, and datasets that support meta-analysis, evidence synthesis, gap maps, and cost-effectiveness analysis, so lessons can be generalized and scaled.

Everything DEVIDENCE produces, from pipelines to data, is a public good.

DEVIDENCE is a joint initiative between the Global Poverty Research Lab (GPRL), Center for Effective Global Action (CEGA), and Innovations for Poverty Action (IPA).

WHAT IS DEVIDENCE

Infrastructure

DEVIDENCE leverages large language models (LLMs), deterministic code, and human-in-the-loop validation to construct and maintain our relational databases. The integrated pipeline is designed to convert published studies and raw survey data into structured, comparable evidence, modeled on how researchers have traditionally done manual evidence aggregation. The pipeline is reproducible, documented, and designed to be run continuously as literature grows:

Step 1: Metadata Collection and Verification

Publication metadata is collected through a combination of LLMs and API connections to external databases, then manually reviewed for accuracy.

Step 2: Structured Data Extraction

Treatment effects and other study-level fields are extracted from the full text of each paper using a combination of LLMs and deterministic code. No extracted value is trusted on first pass; coding scripts re-read each figure at its source, and a second model checks every field against the paper's text. An AI agent orchestrator approves each stage of the extraction process before the pipeline proceeds to the next. Only once this multi-stage verification is complete does a record move on to human validation.

Step 3: Validation with DEVIDENCE Fellows

A cohort of scholars from low- and middle-income countries, convened through the DEVIDENCE Fellows Program, reviews and validates the extracted study-level information. Fellows work asynchronously through an application developed and maintained by the DEVIDENCE team.

Step 4: Cataloguing Microdata Variables

When underlying datasets are available, including household surveys, administrative records, and other individual-level datasets, the variables used in each analysis are systematically catalogued. This includes recording each variable's original name, definition, units, and role within the study.

Step 5: Harmonizing Like Variables

Because studies often measure similar concepts using different definitions, scales, or naming conventions, all related variables are harmonized into a common framework, using economic methods. This allows outcomes and covariates that are substantively comparable but reported under different labels or units to be aligned for cross-study comparison and synthesis.

Step 6: Quality review

Every decision and judgment made by the LLMs is recorded, along with supporting evidence, creating a transparent audit trail for each piece of data. Before any information enters the DEVIDENCE database, humans review this audit trail and approve the AI’s work at key checkpoints, verifying the accuracy and quality of the aggregated data. The end result is a single database researchers can use, along with clear documentation of how each variable of interest was constructed.

Data

DEVIDENCE produces two interconnected databases. Study-Level Data, which encodes information on experimental design, sampling, interventions, outcomes, and effect sizes, extracted directly from academic papers, and Harmonized Microdata, which pulls together the underlying survey and administrative data in a standardized way so that measurements are comparable.

Study-Level Data

Study-Level Data contains 13 thematic modules spanning publication metadata, experimental design, demographics, costing, interventions, data collection, outcomes, and effect sizes. It is the first of its kind to standardize experimental design and treatment effect parameters.

The schema used to collect Study-Level Data combines a standardized set of fields with a flexible reporting structure that is responsive to differences in how data is reported across papers, and built-in conditionalities that ensure that information is captured at a consistent level of detail and reported uniformly across studies. It was built to be interoperable with other evidence aggregation projects from the World Bank, AidGrade, 3ie, J-PAL, and IPA.

Harmonized Microdata

Harmonized Microdata includes demographics, treatment assignment, and key outcomes from all studies for which microdata could be obtained.

Harmonizing some of these variables is a matter of mechanical work: unit conversions, currency deflation, variable renaming. Others require judgment calls; for example, whether two differently-worded survey questions measure the same concept, or whether consumption defined one way in one study matches consumption defined another way in a different study. The construction of every harmonized variable is recorded so that assumptions are visible and users can determine whether they are compatible with their analysis.

As a new initiative, DEVIDENCE’s strategy is to systematically grow the database by literature. We are currently working on adding studies from the following literatures: cash transfers, graduation-style programs, entrepreneurship-promoting programs, microcredit, and soft-skills training.

Meet the Team

Current Contributors

GPRL

Makayla Barker, Navishti Das, Dean Karlan, Michael Mulford, Erin Ntalo, Isabel Oñate Falomir, Alex Rand, Andrea Salem, Levi Salzman, Rakkshet Singhaal, Giuliana Triberti, Chris Udry, Prisha Visveswaran, Lauriane Yehouenou

CEGA

Carson Christiano, Edward Miguel, Sergio Puerto, Jo Weech

IPA

Niall Keleher, Laura Lahoz, Daniel Martinez Enriquez, Kelly Montaño, Karen Gabriela Rojas

Past Contributors

Govind Gupta, Pengyu (Leo) Li, Carolina Ortiz Salazar, Romil Pandey, Irena Petryk, Julius Rueschenpoehler