Exclusion groups

When two experiments run at the same time, a visitor can be part of both. Often this is fine. But if the experiments change the same area of a page, or test related ideas, they can distort each other's results.

An exclusion group solves this. You put the experiments that must not overlap into one group. ABlyft then makes sure that each visitor takes part in at most one of them.

How it worksCopy Anchor Link

For a visitor who qualifies for an experiment in a group, ABlyft decides as follows:

1. If the visitor already takes part in one of the experiments of the group, that experiment stays their experiment. They are not put into any other experiment of the group.
2. Otherwise, ABlyft picks one experiment of the group by chance. The traffic share you set per experiment is the weight: an experiment with 70 % is chosen more often than one with 30 %.
3. The chosen experiment continues with its normal checks, including its own traffic allocation. The visitor is excluded from the other experiments of the group.

Things to know:

• Only experiments that are running or in preview count. Drafts and paused experiments in a group are ignored.
• The draw only considers experiments whose audiences match the visitor. A visitor who does not fit the audience of an experiment is not "used up" by it.
• The traffic share is a probability, not a guarantee. With few visitors, the real split can differ from the set share.
• In preview mode, exclusion groups are not applied, so you can always check your experiment.
• An experiment can be part of several groups. It then has to win in every one of them.

Create an exclusion groupCopy Anchor Link

1. In your project, go to Experiments → Exclusion Groups in the navigation.
2. Create a new group (if the list is still empty, click Create your first exclusion group).
3. Enter a Name and optionally a Description.
4. In the section Mutually Exclusive Experiments, choose at least two experiments and set the Traffic for each. Click Add another experiment if you need more. The status of each experiment is shown next to its name.
5. Make sure the Traffic Sum is exactly 100 %. The bar below turns green when it is correct.
6. Save.

By default, a new entry has a traffic share of 50 %. For two experiments that you want to treat equally, keep 50 / 50. To give one experiment more of the visitors, for example 70 / 30, change the numbers.

If you add or remove experiments, adjust the traffic values so that they add up to 100 %. Changes to a group are published automatically.

Find out which experiments are in a groupCopy Anchor Link

• On the experiment page, the card Status shows a badge such as Part of 1 exclusion group.
• In the experiment list, filter with Part of any exclusion group, or show the column Excl. Groups with the column toggle.

Delete a groupCopy Anchor Link

Select one or more groups in the list and use the bulk action to delete them. The experiments are not deleted, they only leave the group.

Plan your trafficCopy Anchor Link

Because a group splits your visitors between experiments, every experiment in it receives only a part of your traffic. Each experiment then needs more time to collect enough data. Use exclusion groups only where overlap would really harm your results. Use the pre-test calculator to estimate the runtime.

Next stepsCopy Anchor Link