Geospatial Impact Evaluations
Learn more in our #CGDTalks Video
Geospatial impact evaluations (GIEs) rely on subnationally geo-referenced intervention, outcome, and covariate data and quasi-experimental methods of causal inference to measure the intended (or unintended) impacts of development programs.
GIEs seek to mimic the conditions of a randomized control trial (RCT) with observational data. RCTs are powerful because they create conditions under which one can reliably ascertain that individuals’ participation in a program was not correlated with their outcomes. GIEs create similar conditions, but without randomly assigning individuals to treatment and control groups.
For our in-depth exploration of GIEs, please see A Primer on Geospatial Impact Evaluations Methods, Tools, and Impact Evaluations.
Using counterfactuals to find impact
The key is making comparisons across individuals who are sufficiently similar to one another and experiencing changes that are otherwise similar. The best way to make such comparisons is to identify comparison individuals who are geographically close to the program participants, but unlikely to be affected by the program’s presence. Doing so requires geographically precise data on programmatic interventions and their intended (or unintended) outcomes. Such data are rapidly expanding in number, scope, periodicity, and availability.
Rather than using randomization to identify counterfactual cases, GIEs seek to achieve a similar result through one of three methods:
- Strategic subsampling of observational data to identify treatment and control cases that are nearly identical but for the presence or absence of the intervention (e.g. propensity score matching)
- Comparing the pre- and post-intervention change in the outcome of interest for a treatment group relative to a control group (e.g. difference-in-differences, fixed effects)
- Exploiting the discontinuity around a geographic cutoff that is “as-if random” (where the treated cases and control cases on either side of the cutoff are extremely similar across pretreatment covariates)
Long-term Impact Evaluation of the Malawi Wellness and Agriculture for Life Advancement Program
Ariel BenYishay, Kristen Velyvis, Katherine Nolan, Lila Kumar Khatiwada, Carrie Dolan, Danice Brown Guzman, Tom Purekal, Arif Mamun, Sara Wilf
Building on a Foundation Stone: The Long-Term Impacts of a Local Infrastructure and Governance Program in Cambodia
Ariel BenYishay, Brad Parks, Rachel Trichler, Christian Baehr, Daniel Aboagye, Punwath Prum
The impact of an insecticide treated bednet campaign on all-cause child mortality: A geospatial impact evaluation from the Democratic Republic of Congo
Carrie Dolan, Ariel BenYishay, Karen Grépin, Jeffery Tanner, April Kimmel, David Wheeler, Gordon McCord
Parceling out prosperity? An impact evaluation of natural resource sector investments in Liberia
Brad Parks, Jonas Bunte, Harsh Desai, Kanio Gbala, and Daniel Miller Runfola
Final Report: Evaluation of the On-Farm Water Management Program
Ariel BenYishay, Carey Glenn, Seth Goodman, Dan Runfola, Rachel Trichler
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