A company wants to test the effectiveness of a new acne cream....

Question

A company wants to test the effectiveness of a new acne cream. The company recruits 500 girls ages 13 to 17 who have acne. The subjects are randomly assigned into two groups. One group is given the acne cream and the other is given a placebo that looks exactly like the acne cream. Both groups apply the cream daily for two months. Facial photos are taken at the beginning and end of the treatment to compare results.
b. Identify a potential problem with the experimental design being used and suggest a way to improve it.

b. Identify a potential problem with the experimental design being used and suggest a way to improve it.

Accepted Answer

Welcome back, everyone. In this problem, a research team is evaluating a new dietary supplement intended to enhance memory. They select 400 college students aged 18 to 22, all from the same university. The students are randomly divided into two groups one receives the supplement and the other receives a placebo. Both groups take their assigned pills daily for 6 weeks, and memory tests are administered before and after the treatment. What is a potential flaw in this experimental design and how could it be addressed? A says the study only includes college students from one university and including participants from multiple universities and age groups would improve generaliability. B says the study does not use a placebo group, and adding a placebo group would improve the design. She says the study does not measure memory before the treatment and including a pre-treatment test would improve the design, while D says the study does not randomize participants and a random assignment would improve the design. Now here let's look at the information that we have in our problem statement. Now notice here that all students are selected from the same university, OK? And they're also within a narrow age range from 18 to 22. That limits the generaliability of the results to other populations. So that's a flaw, and it's a flaw because this lack of diversity means the findings may not apply to other age groups like older adults or people from different educational backgrounds since they're all selected from college or individuals from other regions, OK, because this is from the same university. So to improve generaliability here, the researchers should include participants from different universities and a wider range of ages to make the results more generalizable. So that means A is the correct answer. No, we can verify that A is the correct answer if we look at the rest of our answer choices. In answer choice B, it says that the study does not use a placebo group, but not in the problem statement we're told that one group received a supplement and the other receives a placebo. So B could not be the correct answer. If we look at C, it says that the study does not measure memory before the treatment, but again, in it we're told that memory tests are administered before and after the treatment. So that's how we know that answer choice C would not be the correct answer. Finally, in answer choice D, it says the study does not randomize participants, but notice here the problem statement says the students are randomly divided into two groups. So we know that D could not be correct either. Therefore, we're sure that answer choice A is the correct choice. Thanks a lot for watching everyone. I hope this video helped.

Key Concepts

Random Assignment

Placebo Effect

Control Group

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