Why is a control group important in an experiment?

Why is a control group important in an experiment?

• A. It increases the total number of variables.
• B. It provides a baseline for comparison to determine the effect of the variable being tested.
• C. It ensures the experiment uses qualitative data only.
• D. It eliminates the need for replication.

Answer: (B)

The main idea here is that a control group provides a baseline for comparison so you can tell whether the treatment actually changes the outcome. By keeping everything the same between the control and the experimental group except for the factor you’re testing, any difference you observe can be attributed to that factor rather than other variables like environment or measurement error. This helps establish cause and effect, not just a correlation. The other options don’t fit because a control group doesn’t increase the number of variables; it helps keep variables constant. It also doesn’t force data to be qualitative only, and even with a control group, replication is still needed to confirm results across trials.

The main idea here is that a control group provides a baseline for comparison so you can tell whether the treatment actually changes the outcome. By keeping everything the same between the control and the experimental group except for the factor you’re testing, any difference you observe can be attributed to that factor rather than other variables like environment or measurement error. This helps establish cause and effect, not just a correlation. The other options don’t fit because a control group doesn’t increase the number of variables; it helps keep variables constant. It also doesn’t force data to be qualitative only, and even with a control group, replication is still needed to confirm results across trials.