How Can I Control What Percentage of Traffic Participates in Tests?

Nelio A/B Testing lets you control what percentage of your visitors are eligible to participate in your running tests.

The Tested Visitors percentage is a global setting, which means it applies to all active tests on your site.

Reducing this percentage can be useful when you want to:

• Run tests on only part of your audience
• Limit quota consumption
• Reduce the number of visitors exposed to tests

How Does It Work?

TIf you set Tested Visitors to 20%, Nelio A/B Testing will make approximately 20% of your visitors eligible to participate in running tests.

For example, if your site receives 100 visitors and Tested Visitors is set to 20%, approximately 20 of them will be eligible to participate in tests.

Visitors who aren’t selected:

• See the original content
• Don’t consume quota
• Don’t affect test results

Note: Being selected for testing doesn’t necessarily mean a visitor will participate in every running test. Other conditions, such as the test scope and segmentation rules, determine whether the visitor participates in a specific test.

How to Change the Percentage of Tested Visitors

To change the global participation percentage:

Use the slider to select the percentage of visitors you want to make eligible for testing.

1. Go to Nelio A/B Testing → Settings.
2. Find Tested Visitors under Tracking.
3. Use the slider to select the percentage of visitors you want to make eligible for testing.
4. Save your changes.

The selected percentage applies globally to your active tests.

Tested Visitors vs. Variant Distribution

Don’t confuse the Tested Visitors setting with variant distribution. They control two different things::

• Tested Visitors determines what percentage of visitors are eligible to participate in your tests.
• Variant Distribution determines how the visitors participating in a specific test are distributed among its control and variants.

By default, visitors participating in a test are evenly distributed among its variants. If you enable Allow custom variant distribution in tests in Nelio A/B Testing settings, you can customize this distribution for individual tests.

For example, you could set Tested Visitors to 20% globally and configure a specific test so that 70% of its participants see the control and 30% see a variant.

🔍 Learn more: Can I Control How Often Each Variant Is Shown to Visitors?