A medical researcher believes that supplements of glucosamine can help to reduce the pain of arthritis. She

would like to test the supplement at two different dosage levels. She designs an experiment as follows to test

her conjecture. She will obtain a group of volunteers who suffer from arthritis. Each patient's condition will be

evaluated by a doctor at the start of the experiment. Volunteers will be randomly assigned to one of two groups.

Each day for the duration of the experiment, patients in group 1 will receive a low dose of glucosamine and

patients in group 2 will receive a higher dose of glucosamine. After a suitable amount of time (two months, for

example), the doctor will evaluate each patient's progress. Based on the amount of inflammation and the

patient's report on the amount of pain, the doctor will give each patient a numerical score to represent their

improvement. She would then compare the amount of improvement for the two groups. Also, she will ensure

that the evaluating doctor and the technicians administering the supplements are blinded to whether patients

receive a low dose or high dose. Identify the flaw(s) in this experiment.