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Randomized Control Trials (RCTs). The What, Why & When of RCTs. What are RCTs?. Treatment Group- It offers treatment.
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What are RCTs? Treatment Group- It offers treatment Random assignment implies that the distribution of the characteristics of the applicants in the treatment and control groups are statistically identical. The only difference is that some got the program while others did not. Take a sample of program applicants Randomly assign them to Control Group- Not allowed to receive treatment during the evaluation period Comparing them gives you the effect of the program
Why RCTs? • Can we compare microfinance clients to non-clients if we want to evaluate a microfinance program? • NO- because we are comparing two different types of people: those who choose to borrow or save, and those who do not. • The ones who choose to participate likely have different business acumen, tolerance for risk, and other characteristics. • By randomly assigning access to financial services, randomized trials ensure that the only difference, on average, between clients and non-clients is access to the program. • I.e. Robustness. Any difference between the groups can be confidently attributed as the impact of the program.
Advantages of RCTs • Relative to results from non-experimental studies, results from experiments are: • Less subject to methodological debates • Easier to convey • More likely to be convincing to program funders and/or policymakers
When to do an RCT • When there is an important question you want/need to know the answer to • Timing not too early and not too late • Program is representative not gold plated – Or tests a basic concept you need tested • Time, expertise, and money to do it right Adapted from Evaluation: What, Why, When, Rachel Glennerster, J-PAL.
When NOT to do a RCT • When the program is premature and still requires considerable tinkering to work well • When the project is on too small a scale to randomize into two “representative groups” • If a positive impact has been proven using rigorous methodology and resources are sufficient to cover everyone • After the program has already begun and you are not expanding elsewhere Adapted from Evaluation: What, Why, When, Rachel Glennerster, J-PAL.