3-way shampoo test

svensven Member
@Perry, in an old post on the board you mention doing a 3 way test of shampoo with 30 volunteers. Do you have any reading material about how to structure such a test? For example would you randomly allocate a shampoo sample to each person, wash their hair and then wait a week and then re wash with the other shampoo to see which one they liked better?
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