An experiment is being designed to compare relief from hay fever symptoms given by a low dose of a drug, a high dose of the drug, and a placebo. Each subject who suffers from hay fever and volunteers for the study is observed on three separate days, with a different treatment used each day. There are two days between treatments, so that a treatment does not have a carry-over effect for the next treatment assigned.
a. What are the blocks in this block design? What is this type of block design called?
b. Suppose the study is conducted as a double-blind study. Explain what this means.
c. Explain how randomization within blocks could be incorporated into the study.