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,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.The amount of improvement for the two groups would then be compared.She will have the evaluating doctor and the technicians administering the supplements blinded to whether patients receive a low dose or high dose.Identify the most serious flaw in this experiment.
A)The experiment is not double blind; doctor evaluating the progress may be biased.
B)There is no placebo group.
C)Volunteers should have been selected randomly.
D)There could be lurking variables.
E)There is no blocking.

Question

Quizplus · Accepted Answer

The most serious flaw in this experiment is that there is no placebo group. Without a placebo group, it is difficult to determine whether any observed improvements in pain and inflammation can be attributed to the glucosamine supplement or simply the natural variability of the disease. A placebo group would allow for a comparison between the supplement and a group receiving no treatment or a harmless treatment, helping to eliminate the placebo effect.

A Medical Researcher Believes That Supplements of Glucosamine Can Help