You wake up one morning feeling slightly under the weather. A close family member enthusiastically suggests that you take some Echinacea, an herb commonly used as a cold remedy. You then decide to design an experiment to test Echinacea and see if this claim is true. You think, "If taken at the beginning of a cold, Echinacea will reduce cold symptoms." You decide to test the effects of Echinacea on 100 people who are experiencing similar cold symptoms. What group would represent an appropriate control in your experiment?

Even though the question is missing the options, since we should choose a control group, it is safe to say it should be 100 sick people given tablets similar to Echinacea but with no herb.

Explanation:

We can reach the conclusion above simply by knowing the basics of experimental design. The most common form of experimental design to prove if something is efficient is done by dividing the subjects being tested into two different groups.

The experimental group is introduced to the change that will or will not produce a certain effect. The control group, however, is not introduced to that change. The purpose is to measure the results obtained from both groups and compare them. If you are using 100 sick people as your experimental group, it would make logical and mathematical sense to use other 100 sick people as your control group. While the first group truly takes the Echinacea tablets (the change introduced), the second group takes a placebo. If the experimental group's members report feeling better from their symptoms while the control group's members report feeling little or no improvement, you'll have successfully proved Echinacea works as a cold remedy.