Design of Studies for Alzheimer's Drug
Factors Affecting Power
A research design to compare three drugs for the treatment of Alzheimer's disease is described here. For the first two years of the study, researchers will follow the subjects with scans and memory tests.
What do you think?
The data could be analyzed as a between-subjects design or as a within-subjects design. What type of analysis would be done for each type of design and how would the choice of designs affect power?
For a between-subjects design, the subjects in the different conditions would be compared after two years. For a within-subjects design, the change in subjects' scores in the different conditions would be compared. The latter would be more powerful.