Twenty-Five Patients at a Large Clinic Volunteer to Participate in a Study

Multiple Choice

Twenty-five patients at a large clinic volunteer to participate in a study focusing on weight loss. These 25 patients had a mean weight loss score of x̄= 4500 g over two weeks. Suppose we know that the standard deviation of the population of weight changes on this particular diet is σ= 100 g. The results of the study were widely critiqued. How could the researchers have improved the quality of their research?

A) By running the study for longer than two weeks
B) By not using a volunteer sample
C) By sampling fewer people to reduce variability
D) None of the above