Define your experiment's audience

After you define the events that make up your experiment, set up the audience eligible for the experiment, also known as targeting. You can open eligibility to all users or target specific groups.

Targeting groups limits experiment exposure to users in specific geographical locations, demographic groups, or users who meet certain usage thresholds in your product, such as power users. Segments are the unique characteristics of your audience you want to target, such as geolocation or device type. All Amplitude user properties and cohorts can define user segments. For any user property in a rule-based segment, Amplitude uses the most recent value the user property received. For more information on segments, go to Segment Overview.

You can include any number of user segments. If a user belongs to more than one segment in an experiment, Amplitude assigns the user to the first segment they match.

Defining your audience also requires that you specify your distribution and rollout:

• Distribution: the percentage split between the control and the experiment group. The default distribution is 50%, so half the audience receives the control and half receives the experiment. You can customize the percentage to put more users in one group. Distribution applies to your targeted audience, not your total user base.
• Rollout: the percentage of your targeted audience that receives the experiment. At 100%, every user in your targeted audience receives either the control or the treatment. Experiment displays the potential number of users who receive the experiment.

Set the target audience for your experiment

1. Create a new experiment or open an existing one.
2. In the Targeting section, click the edit icon.
3. In the Targeting tab, select the bucketing unit you want. Bucketing is typically by User. You can also bucket by groups.
4. Select the users eligible for this experiment. Targeting defaults to All Users. Add a segment to switch to Targeted Users. Targeting all users means every user who triggers the exposure event receives your experiment. Targeted users lets you specify segments of users that receive your experiment.
5. Select the bucketing you want to target. The default is Amplitude ID. You can also select options such as:
   • Device type.
   • Language.
   • Region.
   • Postal code.
6. To customize the distribution percentage, click Switch to custom, then specify the percentages you want.
7. In the All users field, specify the percentage of users that receives the experiment.
8. Click Save & Close or Testers.

After you specify your audience, specify your testers.

Testers

Test your experiment to confirm all aspects work and that the implementation succeeds. Go to Test and Launch Your Experiment for more details about testers.

Boolean logic in segments

Amplitude applies Boolean AND logic to conditions within the same segment. Amplitude evaluates these conditions as if, else if. For example, consider two segments:

Segment 1: users in India who access your site through the web. Segment 2: users on Android devices who access your website through the mobile browser.

With Boolean logic, a user must meet both conditions in a segment to qualify. If a user accesses your website but isn't in India, the user doesn't qualify for Segment 1. If a user accesses your site through an iOS device, the user doesn't qualify for Segment 2.

The if, else if evaluation means Amplitude first checks whether a user meets the conditions for Segment 1. If not, Amplitude checks the conditions for Segment 2.