What are Mutually Exclusive Groups?
Mutually exclusive groups ensure that visitors participate in only one experiment within a group of related tests. This feature is crucial when you need to maintain data clarity and prevent interference between multiple experiments running simultaneously.
IMPORTANT NOTE:
When using mutually exclusive groups, your total available traffic gets divided between experiments
Example: With 1000 daily visitors, two mutually exclusive tests at 50% each means 500 daily visitors per test
When to Use Mutually Exclusive Groups?
Consider using mutually exclusive groups in these scenarios:
Multiple Tests on the Same Page
When running several experiments on a single page
Example: Testing both hero image and headline variations simultaneously
Related User Journey Tests
When experiments overlap in a conversion funnel
Example: Testing different checkout page layouts while also testing payment option displays
How to Create a Mutually Exclusive Group
Navigate to the Global Settings tab in the side menu
Click the Global Settings button
Scroll down to Mutually Exclusive Groups
Click on Add/Manage Groups
Adding Campaigns to a Mutually Exclusive Group
Use the dropdown menu under "Choose a test campaign" to select experiments
Click Add to Group to add the selected campaign
Configure traffic weightage
Example distributions:
Equal split: 50-50 between two tests
Priority split: 70-30 favoring critical tests
You can add multiple campaigns to each priority group
Understanding Priority Groups
Priority groups determine the order in which tests are assigned to visitors
Tests in Priority Group 1 take precedence over tests in Priority Group 2
Lower priority groups only considered if higher ones don't match
You can add new priority groups by clicking Add New Group
Example: Homepage Testing Plan
Priority Group 1
Test A: Hero Image Variations (50% traffic)
Test B: Headline Copy Test (50% traffic)
Priority Group 2
Test C: CTA Button Colors (100% traffic)
How visitors are assigned:
Visitor lands on homepage
System checks Priority Group 1:
50% chance of seeing Hero Image Test
50% chance of seeing Headline Copy Test
If visitor doesn't qualify for Group 1:
They'll see the CTA button test
Key Points
Individual experiment rules (e.g. targeting, traffic allocation) are checked first
If eligible, they're assigned to ONE test within their matched priority group
Only if visitor doesn't qualify for higher priority groups, they move to lower ones
Visitor assignments remain consistent throughout their journey for reliable data collection
Draft tests are not included as part of the ongoing live traffic allocation in the group. Therefore, if you have four tests in the group and only two are live (while the other two are in draft), 50% of traffic goes to each live test and none to the draft tests
If you pause or complete an experiment while others in the group keep running, returning visitors from the stopped one can be re-assigned to a sibling experiment. So if you want a clean read, avoid stopping one test in a group mid-flight while the others continue
Exclusion is scoped to the group only - there's no site-wide "one test at a time" setting. But a single group can span experiments on completely different pages. So if you want homepage and checkout tests to be mutually exclusive, putting them in the same group is the way to get that guarantee.