At the end of the three months, a skin specialist rated skin health on a scale of 1 to 10 for each of the participants. Researchers found that the distracted group’s average assessment score was 4 poi...At the end of the three months, a skin specialist rated skin health on a scale of 1 to 10 for each of the participants. Researchers found that the distracted group’s average assessment score was 4 points lower than the average assessment score for the group that was not distracted. Explain why it would be good for the researchers to use random assignment to put each volunteer in one of the experimental groups.
