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Twenty volunteers were assigned at random to one of two groups (10 people in each group). One group would take Vitamin C for two weeks, while the second group would take a placebo. At the end of the study, the proportion of colds in the two groups will be compared.
-Can a conclusion that taking Vitamin C causes a change in the risk of a cold?
A) A cause and effect relation might be concluded because the study had a control group.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because the study was an observational study.
D) A cause and effect relation cannot be concluded because exposure to other people with colds was not controlled.

Question

Quizplus · Accepted Answer

A cause and effect relation might be concluded because the study was a randomized experiment. Random assignment of participants to the treatment or control group helps to ensure that any differences observed at the end of the study are due to the treatment itself (in this case, Vitamin C) and not to other factors.

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