Which of two brands (X or Y) of electric razor shaves closer? Researchers want to design and carry out an experiment to answer this question using 50 adult male volunteers. Here’s one idea: Have all 50 subjects shave the left sides of their faces with the Brand X razor and shave the right sides of their faces with the Brand Y razor. Then have each man decide which razor gave the closer shave and compile the results.

a. Identify any flaws you see in the proposed design for this experiment.

b. Describe how you would design the experiment. Explain how your design addresses each of the problems you identified in part (a).