Question

determine whether the study is an experiment or an observational study, and then identify a major problem with the study. a medical researcher tested for a difference in systolic blood pressure levels between male and female students who are 12 years of age. she randomly selected four males and four females for her study. this is an observational study because the researcher applies a treatment to the individuals. what is a major problem with the study?
a. there is no blinding, which has a high chance of leading to bias.
b. this is a convenience sample with voluntary response, which has a high chance of leading to bias.
c. the sample includes male and female students.
d. the sample is too small.

Explanation:

1. First, determine the study type: The researcher is observing blood pressure differences between male and female students without applying a treatment (the initial thought of "applies a treatment" was incorrect; actually, she's just testing existing differences). So it's an observational study.
2. Now, analyze the problem with the study: The sample size is 4 males and 4 females (total 8), which is very small. A small sample size can lead to inaccurate results and low statistical power.

• Option A: Blinding is more relevant in experiments with treatments, not observational studies here.
• Option B: There's no indication of convenience or voluntary response sampling (she randomly selected).
• Option C: Including both genders is a strength for comparing, not a problem.
• Option D: The sample (8 students) is too small, which is a major issue as it may not represent the population well.

Answer:

D. The sample is too small