Researchers from a pharmaceutical company have developed a n

Researchers from a pharmaceutical company have developed a new drug that they believe will relieve long-term depression. They wish to carry out a clinical trial to compare its efficacy with an existing drug. It is known that of the drugs currently available, some will alleviate symptoms while they are being taken. Which of the following three designs would you recommend? . A group-comparative design . A matched pairs design . A crossover design Briefly justify your choice, commenting on each of the three designs.

Solution

In a group comparative design, experimental units are randomly assigned to treatment conditions. Randomization provides some control for lurking variables. A cross-over design is not possible because medicines are supposed to relieve long-term depression. In a matched pairs design, experimental units within each pair are assigned to different treatment levels. And here, this design should be used.