Mutually Exclusive Experiments
Definition
The Mutually Exclusive Experiment (M2E) feature allows you to run multiple experiments simultaneously on the same audience and with the same primary goal—without introducing UX conflicts or data bias.
➡️ To learn more about the benefits and potential pitfalls of this feature, see read our blog article: Mutually Exclusive Experiments: Preventing the Interaction Effect
Configuration
Creating an Exclusion group
To create a group:
Go to the Campaigns dashboard
Click the three dots next to the campaign.
Two options are possible: Add to exclusion group or Manage exclusion group, depending on whether the campaign is already part of a group.
To exclude a test campaign from another and create a group, select the option Add to exclusion group.
A modal appears. You are already located in the group creation option.
Give the group a clear name (for example, Homepage tests or Cart improvements) to help track included campaigns.
Open the dropdown menu to select the other campaigns to include.
The list is limited to 12 results by default, but you can use the search bar to find specific experiments.

Select all the campaigns you want to include in the group.
Click Validate selection to add the selected campaigns to the group.
Traffic will be split across all campaigns in the group.
To define traffic manually, toggle on Custom allocation. This is useful if some campaigns run on deeper pages with lower traffic.

Click Save to confirm the configuration.
Adding to an existing Exclusion group
If the exclusion group is not locked, you can add additional tests:
Go to the Campaigns dashboard
Click the three dots next to the campaign.
Two options are possible: Add to exclusion group or Manage exclusion group, depending on whether the campaign is already part of a group.
To exclude a test campaign from another and create a group, select the option Add to exclusion group.
A modal appears.
Select Add to existing group tab.

In the drop down list, select an available group (unlocked).
Click Save
The test will be added to the group and its traffic allocation adjusted accordingly.
Group management
In the Campaigns dashboard, go to the Exclusion group tab to view and manage your groups. The number in parentheses indicates how many exclusion groups exist.
Click Manage next to a group to view or edit it, depending on its status.
Unlocked group
An exclusion group remains unlocked until at least one of its campaigns is live. While unlocked, you can:
Add or remove tests
Activate QA mode (by enabling IP address, URL or cookie targeting) without locking the group
Locked group

Once any campaign in the group is live, the group becomes locked.
By clicking on the manage button, you can still:
View its configuration
Delete the group if all tests are paused
You cannot:
Modify the configuration
Relaunch paused campaigns from a locked group that has been deleted (you must duplicate them first)

Deleting a group
To delete a group:
All campaigns in the group must be paused
If the group was unlocked, deleting it has no impact on campaign configuration
If the group was locked, paused campaigns cannot be relaunched to avoid allocation issue— the platform will invite you to duplicate the campaign instead.
Reporting indication
In the Reports tab, a message appears under the number of visitors to indicate the test was part of an exclusion group. Keep in mind that traffic volumes may differ from standalone experiments.

M2E allocation functioning
When multiple campaigns are mutually exclusive, the way traffic is allocated depends on their targeting and page coverage.

This diagram can be described in one sentence: if your targeted page isn’t the same for all campaigns of the group, part of the traffic landing on your website won’t be assigned to the desired campaign if visitors are bouncing.
On the Homepage, 33% of the traffic is allocated to campaign 1, and 66% to the 2 others. It doesn’t mean that 66% of the traffic will be assigned to the other campaigns, as among these visitors, some may not enter the targeting of the other campaigns.
Allocation scenarios
Same targeting on the same page
Traffic is evenly distributed across all campaigns of the group. As your targeting conditions are the same, the exact same numbers of visitors will be assigned to each campaign.
Different targeting on the same page
Traffic is split evenly accross the group campaigns, but final traffic assignments vary by campaign targeting rules of the group.
Same targeting on different pages
As your Exclusion group contains several campaigns, when landing on one of the targeted page, your visitors, even if corresponding to the targeted audience, might be allocated to another campaign. Thus, if bouncing, they will never reach their allocated campaign and the number of visitors being assigned to the reporting will never be the same.
Different targeting on different pages
Use separate campaigns instead—M2E adds no value in this case
Use cases
#1 Avoiding data bias across similar campaigns
As a User I need to launch several tests at the same time on the same page. Those campaigns shouldn’t enter into UX conflict as they are acting on different elements but my primary goal is the same for all campaigns.
In order to avoid any data biases I’d prefer making them mutually exclusive and do a proper analysis at the end.
#2 Preventing UX conflicts
As a User I need to test different parts of my page and I’m afraid of UX conflict between those parts. Thus, to avoid any bad user experience I would better use the Mutually Exclusive Experiments feature and be more confident during the QA.
#3 Balancing traffic across different pages
As a User, I need to launch several tests at the same time on my website and all of them have the same primary goal. One campaign applies on the Home page and the other on the Product page. I know that I’ll have way more traffic on the HP than on the PP. Thus, I can use the Custom Allocation functionality of the Exclusion group to assign more traffic to my PP campaign than my HP campaign.
FAQ
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