4) Suppose two research teams, call them A and B, are interested in evaluating a

Question

4) Suppose two research teams, call them A and B, are interested in evaluating an intervention for weight loss using a randomized, placebo-controlled trial. Each team is interested in testing the null hypothesis that mean weight loss during the trial is the same between the intervention and placebo groups versus the alternative that the mean weight loss during the trial is different in the intervention and placebo groups. Both research teams plan to use the same statistical test, pre-specify the probability of a Type I error to be 0.05, and think the difference in mean weight loss during the study between the intervention and placebo groups will be 10 pounds If both research teams also think the standard deviation of weight loss during the study in both groups will be 2 pounds but team A plans to recruit 100 participants per group. and team B plans to recruit 200 participants per group, which team (A or B) has designed a study with higher power? Explain a) b) (*1 point) Now, instead, suppose both research teams plan to recruit 100 participants per group. Team A plans to recruit participants from a subgroup of the population where they think the standard deviation in weight loss during the study in both groups will be 1 pound. Team B plans to recruit participants from a subgroup of the population where they think the standard deviation in weight loss during the study in both groups will be 3 pounds. Which team (A or B) has designed a study with higher power? Explain

Explanation / Answer

a) power is directly proportional to sample size
hence
Team B has higher power

b)
power is inversly proportional to sample standard deviation
hence
Team A has higher power

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