Control Group
01 Definition
Control Group meaning: The unchanged group in a test, used as a baseline to compare against.
A control group receives the original experience with no changes while other groups see a variant. Comparing the variant to the control shows whether the change caused a difference in the outcome. Without a control, you cannot separate the effect of your change from seasonality, traffic shifts, or other outside factors.
Also called
Why it matters
How Control Group fits the work
The control group is what lets a test claim cause and effect, because it isolates your change from everything else happening at the same time.
In context
Half of visitors saw the redesigned pricing page while the control group kept the current layout for a fair comparison.
Practical note
Keep the control and variant groups running over the same period and drawn from the same traffic. Splitting them across different weeks can confound the comparison.