Evidence-Based Practice / Unit 22 EBP 3185 short lesson, about 20 seconds
Blocking
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The idea
Blocking groups participants who are alike on some variable before assignment, so that variable cannot explain the difference between arms.
In practice
Grouping by unit before assigning, so that ward differences fall evenly across both arms.
Where people slip
Blocking controls the variable you blocked on and nothing else. It is not a substitute for randomisation, which handles what you did not think of.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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