Randomized Control Trials
Randomized Control Trials (RCTs) are considered the 'gold standard' for impact evaluation.
The topic of randomized controlled trials is covered in many papers, handbook, and textbooks. Links to several of these are provided below (in the "external links" section).
Individual-level RCTs
Individual-level RCTs are impact evaluation design where the outcomes are measured on an individual basis. Randomization for individual-level RCTs are also done on an individual (per participant) level.
Clustered RCTs
Clustered RCTs are a type of RCT in which randomization and outcome measurement are done on the basis of a group i.e. cohort, villages, etc.
Randomized Phase-In
Roll-out of the intervention is randomized. This is typically done at the cluster-level. For example, an intervention is intended to treat 100 villages. 50 villages are randomly selected to receive interventions in year 1, and 50 villages are selected to receive interventions in year 2 (and therefore serve as a control group in year 1). A primary advantage of the randomized phase-in is that it is easily applied to project implementation schedules (as roll-outs typically happen over multiple years). A primary disadvantage is that once the intervention is fully rolled-out, there is no remaining control group, and thus no way to measure long-run effects.
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This article is part of the topic Impact Evaluation Design
Additional Resources
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External links
http://www.worldbank.org/en/programs/sief-trust-fund/publication/impact-evaluation-in-practice