In a study of whether taking a garlic supplement reduces the risk of getting a cold, 146 participants were randomly assigned to either a garlic supplement group or to a group that did not take a garlic supplement (“Garlic for the Common Cold,” Cochrane Database of Systematic Reviews, 2009). Based on the study, it was concluded that the proportion of people taking a garlic supplement who get a cold is lower than the proportion of those not taking a garlic supplement who get a cold.
a. What claim about the effect of taking garlic is supported by the data from this study?
b. Is it possible that the conclusion that the proportion of people taking garlic who get a cold is lower than the pro-portion for those not taking garlic is incorrect? Explain.
c. If the number of people participating in the study had been 50, do you think that the chance of an incorrect conclusion would be greater than, about the same as, or lower than for the study described?