ACT Preparation / Unit 20 ACT 1914 short lesson, about 20 seconds
Random Assignment
Captions available
The idea
Random assignment places subjects into treatment groups by chance, so that other differences between subjects spread evenly and only the treatment differs systematically.
In practice
Drawing names from a hat to decide who gets the new study method is random assignment.
Where people slip
Letting volunteers choose their own group lets their differences, such as motivation, travel with the treatment.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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