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Select a Professional Development Module:
Key Topics Strategy Scenario Case Study References

Introduction  |  Step 1  |  Step 2  |  Step 3  |  Step 4  |  Step 5  |  Step 6  |  Step 7

Step 6: Maximize the efficiency of your sample.

Given that your unit of randomization is the classroom (see Step 4), you decide that you need as many classrooms as possible in the intervention and control groups. You decide to randomly assign 40 classrooms to the intervention group and 40 to the control group. Then, to maximize efficiency (that is, maintain as high power as possible without adding needlessly to the costs by over-sampling the secondary units of analysis), you decide to select 5 students per teacher.