> ## Documentation Index
> Fetch the complete documentation index at: https://confidence.spotify.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Mutually Exclusive Experiments
> Use exclusivity groups to prevent users from being exposed to multiple conflicting experiments at the same time.
Make experiments exclusive to other experiments by ensuring that
they have at least one exclusivity group in common. For example, make two A/B
tests exclusive to each other by adding the same exclusivity group to both A/B
tests. No overlap means that no user or other entity is in both of these
experiments at the same time. See the [audience](./audience) page on
experiments for more information about exclusivity when running experiments.
Using exclusivity groups, you can coordinate experiments that change the same or similar parts of an
experience and make them exclusive to each other.
For example, use exclusivity if you want to run multiple related experiments, but you want to only
expose users to one of the experiments.
If you don't make the experiments exclusive to each other, all the multiple experiments can expose
a given user.
Watch this video to get a quick overview of how to use exclusivity groups to coordinate experiments in Confidence.
## Exclusivity Groups
By using several exclusivity groups, you can create sophisticated coordination
of experimentation programs. For example, a set of A/B tests can be exclusive to
each other, but be randomly overlapping with another set of experiments, where
the experiments in the second set are also exclusive to each other.
Read more about exclusivity groups in the [surface documentation](/docs/surfaces/introduction).
On the surface page under **Settings**, you can configure
exclusivity groups to be `suggested`. Suggested exclusivity groups are
automatically added to the experiment when you add the experiment to the
surface.
## How Exclusivity Works
If you want two experiments to be exclusive to each other, there must be
enough users to allocate to both experiments. If there aren't enough users to
allocate, the experiments aren't able to run at the same time. You define how
much of the audience to allocate to an experiment by setting the
[allocation](/docs/flags/audience#allocation).
For example, these two experiments can run at the same time, and
be exclusive to each other:
* Experiment A: 50% allocation, exclusivity group `A`
* Experiment B: 50% allocation, exclusivity group `A`
These two experiments aren't able to run at the same time since there aren't
enough users to allocate to both experiments:
* Experiment A: 50% allocation, exclusivity group `A`
* Experiment B: 70% allocation, exclusivity group `A`
Confidence takes inclusion criteria of the audience into account when
allocating users to experiments. If the audience of experiment A is already
exclusive to the audience of experiment B based on their inclusion criteria,
then experiment A is able to run at the same time as experiment B even if
their allocations are larger than 100%. For example:
* Experiment A: 50% allocation, exclusivity group `A`, inclusion criteria `country = US`
* Experiment B: 70% allocation, exclusivity group `A`, inclusion criteria `country = SE`
### When Experiments should be Mutually Exclusive
In certain situations, being in multiple related experiments at the same time can lead to a poor
and unexpected user experience because of dependencies among tests.
Examples of when you should consider using exclusivity to avoid conflicts between experiments:
* If experiments are using the same flag, for example to alter the ranking of
search results. Since only one experiment can decide the search rank for one
user at one time, exclusive experiments allow several experiments on
search rank simultaneously.
* If the variants of the experiments can interfere with each other. For example, if one experiment changes the background color of a page (using flag A), and
another experiment changes the text color of the same page (using flag B).
In other cases it may not be as obvious if you should make the experiments
exclusive to each other or not.
A rule of thumb is to ask the question:
> If these experiments run in sequence after each other, is it fine to
> ship the winning variants from each experiment without testing them
> together first?
If the answer to that question is *"Yes"* then it's fine to let the experiments
overlap and run them at the same time.
If the answer is *"No"*, you should either test the changes in combination or
run them separately and non-overlapping by making sure that the experiments are
using the same exclusivity group.
If you test them separately, make sure that you then run a follow-up experiment
where you test the promising cells from each experiment in combination with
each other. What combinations to test depends on what treatment
cells from the two experiments that can co-exist in a meaningful way.
A rule of thumb is that you should run overlapping experiments when possible to save
space for more simultaneous product evaluations.
## Make an Experiment Exclusive to Other Experiments
To make an experiment exclusive to other experiments with a certain exclusivity group,
follow these steps.
1. Go to Confidence and find the A/B test or rollout you want to make exclusive to other experiments.
2. Select the surface on which the exclusivity group lives.
3. Select the exclusivity group you want to use.
4. Click **Save**.
## Coordinate Experiments Across Multiple Surfaces
Coordinate experiments across multiple surfaces by using exclusivity groups from more than one surface.
Watch this video to build intuition for advanced experiment coordination in Confidence.
## Related Resources
Step-by-step exclusivity guide
Configure exclusivity groups
Configure experiment audience
Run your experiment