A beauty product company conducts a study to test the effectiveness of a new shampoo to control split ends. One hundred subjects have volunteered to take part in the study, and will be split into a treatment group and a placebo group. The study leader will assign the subjects to the groups randomly using slips of paper. Which reason identifies why randomization is important?
Answer
A
It is important to make sure that groups have 50 people each.
B
It is important to make sure that the first 50 people to volunteer are not all in the same group.
C
It is important to make sure that people who do not currently have many split ends are placed in the placebo group.
D
It is important that subject characteristics such as hair length, hair color, and gender are distributed equally among the treatment groups.
Explanation
Random assignment helps distribute participants’ characteristics across the treatment and placebo groups, reducing the chance that differences between the groups affect the results. For example, hair length, hair color, and gender should be represented similarly in both groups. Randomization does not guarantee exactly equal numbers or require assigning people based on how many split ends they have.
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