Evaluation FAQ: What Sample Size Do I Need for an Impact Evaluation?
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Author(s): MEASURE Evaluation
Year: 2015
An appropriate study sample size and method of selection is critical to the success of any evaluation. In an impact evaluation, with a comparison drawn between a treatment group and a comparison group or showing a change over time, the following factors should be considered during the design phase. This will ensure that an adequate sample is selected to answer your primary evaluation questions.