# Mutually Exclusive Experiments
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](https://www.abtasty.com/blog/mutually-exclusive-experiments/)
## Configuration
### Creating an Exclusion group
To create a group:
{% stepper %}
{% step %}
Go to the Campaigns dashboard
{% endstep %}
{% step %}
Click the three dots next to the campaign.
{% endstep %}
{% step %}
Two options are possible: **Add to exclusion group** or **Manage exclusion group**, depending on whether the campaign is already part of a group.
{% endstep %}
{% step %}
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.
{% endstep %}
{% step %}
Give the group a clear name (for example, *Homepage tests* or *Cart improvements*) to help track included campaigns.
{% endstep %}
{% step %}
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.
{% hint style="info" %}
You cannot add a campaign if:
* It is already part of another group
* It is live or has a start date set
* It has already received traffic
To view only eligible tests, enable the **Show available tests only** option.
{% endhint %}
{% endstep %}
{% step %}
Select all the campaigns you want to include in the group.
{% endstep %}
{% step %}
Click **Validate selection** to add the selected campaigns to the group.
Traffic will be split across all campaigns in the group.
{% hint style="info" %}
The more campaigns you include in a group, the more traffic is split—so reaching statistical significance may take longer. For example, two campaigns may double the time needed to gather reliable data.
{% endhint %}
{% endstep %}
{% step %}
To define traffic manually, toggle on **Custom allocation**. This is useful if some campaigns run on deeper pages with lower traffic.
{% hint style="info" %}
**Custom allocation limitations:**
* You cannot assign more than 100% total traffic
* No campaign can receive 100% of the traffic
* Allocation cannot be changed once the group is locked
{% endhint %}
{% endstep %}
{% step %}
Click **Save** to confirm the configuration.
{% endstep %}
{% endstepper %}
### Adding to an existing Exclusion group
If the exclusion group is not locked, you can add additional tests:
{% stepper %}
{% step %}
Go to the Campaigns dashboard
{% endstep %}
{% step %}
Click the three dots next to the campaign.
{% endstep %}
{% step %}
Two options are possible: **Add to exclusion group** or **Manage exclusion group**, depending on whether the campaign is already part of a group.
{% endstep %}
{% step %}
To exclude a test campaign from another and create a group, select the option **Add to exclusion group**.
A modal appears.
{% endstep %}
{% step %}
Select **Add to existing group** tab.
{% endstep %}
{% step %}
In the drop down list, select an available group (unlocked).
{% hint style="info" %}
To view only eligible groups, enable the **Show available tests only** option.
{% endhint %}
{% endstep %}
{% step %}
Click **Save**
The test will be added to the group and its traffic allocation adjusted accordingly.
{% endstep %}
{% endstepper %}
## 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
| Targeting and page overlap | Result |
| -------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 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 What type of campaign can be made mutually exclusive?
You can add to the exclusion group experiments campaigns (test campaigns) such as A/B Test and Multipage Tests
How are cookies affected?
Once a visitor is assigned to a test in the group, the assignment is stored in a cookie. As long as the cookie persists, the visitor remains assigned to that test.
What happens when my visitor lands on my website?
The AB Tasty tag randomly assigns the visitor to one of the available tests in the exclusion group.
The visitor must meet the targeting criteria to see the test
What about QA?
We advise you to perform your QA before pushing a campaign to a group.\
If not, when using the QAA, you can assign yourself to the campaign by clicking on the "Force Display" CTA.
\
Also, when looking at ABTasty.results, you might not be assigned by your campaign if it's part of an exclusion group. For such reason, you can see a new rejected reason : `exclusion_group_rejected`.\
To be assigned to the campaign, you can either:
* Remove your AB Tasty cookies and refresh the page (random allocation to campaign will be played again since you'll have a new visitorId)
* Force the display to the campaign thanks to the QAA
What happens to the traffic allocation if I pause a campaign?
If you pause a campaign in an exclusion group, the traffic allocation remains unchanged. The paused campaign's traffic percentage is still accounted for, preventing disruptions in visitor experience and data integrity when pausing or launching campaigns.
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