Why is the control and experimental group needed for an experiment?
The control group is necessary to know if the factor being tested is making a difference in the experimental group. Both should be subject to the same conditions, except for the one condition or factor being tested on the experimental group. Differences between the outcomes of the two groups, good or bad, can then be attributed to the one factor that is different. Without the control, it would be most difficult to tell what the factor being tested had done, because it’s not really possible to tell what would have happened without it.
