Which statement explains the purpose of a control group?

• A. Help avoid any need for statistical analysis.
• B. Define the dependent variable more precisely.
• C. Provide a baseline to compare results with the variable being tested.
• D. Guarantee that the hypothesis is true.

Answer: (C)

The idea behind a control group is to have a standard for comparison so you can see what happens when the independent variable isn’t used. In an experiment, you change one thing to test its effect, and you measure what happens to the outcome. The control group goes through all the same steps and conditions as the test group, but without the change to the independent variable. Because of that, any difference in results between the groups can be attributed to the variable you’re testing, giving you a baseline to compare against.

This doesn’t guarantee that your hypothesis is true—results can still vary by chance, so statistics are used to judge significance. It also doesn’t define the dependent variable—that’s what you’re measuring—and it doesn’t eliminate the need for analysis.