Researchers Set Up a Study to Determine Whether Large Doses

question 30

Multiple Choice

Researchers set up a study to determine whether large doses of a nutritional supplement would shorten the length of time it takes to recover from a cold. Three thousand volunteers were split into two groups. For two weeks, members of group A took 3,000 mg of the supplement daily. Group B received 3,000 mg of a placebo (sugar pill) . At the end of the two-week period, the researchers inserted live cold viruses directly into the noses of all the volunteers. The volunteers in both group A and group B continued to take their daily pills. All the volunteers got colds, and there was no significant difference in the length of time the colds lasted.
-To have confidence that the results of the experiment were valid, you'd also want to know

• A) whether any volunteers had colds at the start of the experiment.
• B) whether the volunteers exercised daily.
• C) whether the volunteers all worked for the same company.