• Optimizely Web Experimentation
  • Optimizely Performance Edge
This article will help you:
  • Change the percentage of total traffic that's eligible to enter your experiment
  • Change what percentage of your experiment traffic sees each variation
  • Stop a variation

By default, Optimizely allocates 100% of visitors to experiments and distributes traffic equally among variations. You can reallocate and redistribute traffic (described below), but we don't recommend this for running experiments. Here's how to send all traffic to a winning variation in an experiment.

If you're using Optimizely Performance Edge, certain features described in this article will behave differently than in Optimizely Web Experimentation. Optimizely Performance Edge is a lightweight experimentation product that delivers significantly faster performance than previous versions of Optimizely. It does this by relying on a streamlined "microsnippet" which limits the range of available features.

You'll see this notation edge-info.jpg whenever the text describes a feature that works differently in Performance Edge than it does in Web.

Read on to learn how to control traffic allocation and distribution in Optimizely.

Re-allocate and re-distribute traffic

To change traffic allocation and distribution for variations in Optimizely:


  1. From the Experiments dashboard, navigate to your experiment.

  2. Under Manage Experiment, select Traffic Allocation.

    You can also change your traffic allocation and distribution directly from the Results page. Click Edit Experiment > Traffic Allocation.

edge-info.jpg If you are using Performance Edge, a change to a single variation’s traffic distribution could result in all visitors being re-bucketed. For that reason, changing the traffic for a live experiment in Performance Edge is strongly discouraged.

  1. In the Traffic Allocation dialog, under Experiment Traffic Allocation, change the percentage of eligible visitors who enter your experiment. If you choose 50%, half of the visitors who land on your page and meet your audience conditions will enter the experiment and be tracked in results.

    Under Variation Traffic Distribution, you can adjust the percentage of traffic that will be bucketed into a particular variation. For example, if you have four variations and the traffic is distributed equally, each new visitor has a 25% chance of being placed into each variation.

    Changes to traffic distribution will only affect new visitors. Existing visitors (whether or not they were bucketed in a variation) will keep seeing the same variation, even after you change traffic distribution. Visitors who are excluded from the experiment will always be excluded.

    Stopping variations completely, however, can potentially affect all visitors. If, for example, you were to stop a variation in a Web experiment, returning visitors who have previously been bucketed into an experiment will not see the variation to which they’d been assigned, and will instead get the same experience as everyone else.

    edge-info.jpg With Performance Edge, however, this would not be the case. Unlike Web, Performance Edge does not use sticky bucketing. If you were to set traffic allocation of a particular variation to zero in a Performance Edge experiment, returning visitors who have previously been bucketed into an experiment would not see the variation they'd originally been assigned, and instead will be re-bucketed into another variation.

  2. Click Save.

If you are changing the traffic allocation from a previously published traffic allocation, Optimizely will add a yellow "changed" label indicating that this traffic allocation has not been published yet.


You will need to click on "Publish Experiment" for the new traffic allocation to take into effect.

Changing traffic allocation may affect your experiment results and make it difficult to interpret them correctly.

Stop a variation edge-info.jpg