A study claims that the combination of vitamin C with vitamin E is more effective for preventing the flu than vitamin C alone. In the study, a group of researchers studied 1132 subjects. The subjects were randomly assigned to one of the three study groups. The first group of 310 subjects were instructed to take 600 mg daily of vitamin C. The second group of 418 subjects were instructed to take 600 mg of vitamin C and 200 IU of vitamin E daily. The third group of 404 subjects were instructed to take 600 mg of vitamin C and 400 IU of vitamin E daily. The incidence of flu over a season was recorded. All subjects knew which treatment they were receiving. i) In this study, which group is the control group? Blank 1 A) Group 2 B) the 1132 subjects C) Group 3 D) Group 1 E) There is no control group. ii) The study is Blank 2 A) double-blind B) not an experiment C) not blind D) blind, but not double-blind E) none of the above

1) In this study, the control group is the first group of 310 subjects that were instructed to take only 600 mg daily of vitamin C. (Option C; that is, group 1)

2) The Study is not Blind. (Option C)

Step-by-step explanation:

In experimental setup to test a theory, A control group is the set of experimental participants that the theory to be tested isn't applied upon.

In the case of testing a new treatment, the control group is the group that the new treatment isn't administered to.

For this question, the experiment was setup to test the effectiveness of a combination of vitamin A and vitamin E in treating flu cases rather than using vitamin C alone. Group A is the only group that only the old treatment alone is applied to; group 1 participants received no dosage of the new combination of treatments to be tested involving vitamins A and E unlike the two other groups.

It is obvious now why the experimental participants of group 1 are the control group.

2) A blind experiment/study is one in which the participants don't know which group they belong to, whether they are in the control group or the other experimental group. Like in this case, if this was a blind study, the participants wouldn't know which group they belonged to or which treatment is administered to them.

A double-blind experiment/study is one in which both the conductors of the experiment and the participants in the experiment wouldn't know which group any participant is. The conductors wouldn't know which participants were in the control or treatment group and the participants too wouldn't have an idea which whether they are in the control or treatment group.