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Randomized Evaluation: Dos and Don’ts An example from Peru Tania Alfonso Training Director, IPA.

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Presentation on theme: "Randomized Evaluation: Dos and Don’ts An example from Peru Tania Alfonso Training Director, IPA."— Presentation transcript:

1 Randomized Evaluation: Dos and Don’ts An example from Peru Tania Alfonso Training Director, IPA

2 Outline Design Implementation Analysis

3 Outline Design – Research question – Power – Randomization – Sampling Implementation Analysis

4 Research question Do make sure the research question is policy relevant Do make sure your indicators are answering your research question

5 Power Don’t conduct an under-powered evaluation – What does it mean to be under-powered? – Sample size and power

6 Power Do power calculations first – Effect size – Sample size – Getting data – (What will take-up be?)

7 Power Do cluster your standard errors when doing power calculations – Bad examples (two districts, 10,000 people)

8 Randomization Do Ensure balance – Stratification – Re-randomizing – Costs and benefits

9 Sampling Do make sure your sampling frame is as close to your target population as possible – Effect size

10 Outline Design Implementation – Measurement – Monitoring – Attrition Analysis

11 Measurement Don’t collect data differently for treatment and control groups – Introducing bias

12 Measurement Don’t use as your primary indicator something that may change with the intervention, even when the outcome does not

13 Monitoring Do monitor your intervention to ensure the treatment groups are receiving the treatment, and control groups are not – Contamination

14 Monitoring Do collect process indicators to unpack the black box

15 Attrition Do whatever it takes to minimize attrition – Attrition bias

16 Outline Design Implementation Analysis – Treatment integrity – Attrition – Final outcomes – Subgroup analyses – Covariates

17 Integrity of design “Once in treatment, always in treatment” Don’t switch treatment or control status, based on compliance – Intention to Treat – Treatment on Treated

18 Attrition “Once in sample, always in sample” Do not ignore “attritors” – Attrition bias

19 Attrition Don’t relax just because rates of attrition are the same in treatment and control groups – How do we test – How do we know

20 Final outcomes Don’t run regressions on 20 different outcomes and only report on 1 or 2 “significant impacts” Do report on all outcomes

21 Sub-group analysis Don’t run regressions on 20 different subgroups and only report on 1 or 2 “significant impacts”

22 Covariates Do specify the regression(s) you plan to run beforehand Do include covariates that you stratified on and those helpful for absorbing variance.

23 External Validity Do be modest about the external validity of your results – Consider the context (needs assessment) – Consider the process (process evaluation)

24 Cost effectiveness Do have listened to Iqbal’s lecture yesterday – Not sure if he is presenting or covered this…just a guess…


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