This article will help you:
  • Determine what percentage of your total traffic is eligible to be in your experiment
  • Determine what percentage of your experiment traffic sees each variation
  • Pause a variation
  • Auto-allocate traffic to the "winning" variation for an experiment

By default, Optimizely allocates 100% of visitors to experiments and distributes traffic equally among variations. Read on to learn how to control traffic allocation and distribution in Optimizely classic.

Re-allocate traffic

Here's a short video about how to set your traffic allocation.


To change your traffic allocation:

  1. In Visual Editor, click Options > Traffic Allocation.

    Or, from the Home page, choose an experiment to open the Experiment Details sidebar. Next to Traffic Allocation, click Edit.

  2. Drag the slider to increase or decrease the percentage of traffic to include in the 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.

  3. Click each box to change the percentage of visitors who should see a given variation. The total of your percentages must always equal 100%.

Changes made to the overall experiment traffic allocation only affect new visitors. Existing visitors (whether or not they were bucketed in a variation) will continue to see the same variation, even after you change the traffic allocation. Visitors who are excluded from the test will always be excluded, even if you change the overall traffic allocation to 100%.

Changing the allocation between variations after you've started your experiment will affect your results. To preserve your data integrity, we don't recommend changing traffic allocation after you've started an experiment. When you change a variation’s traffic allocation mid-experiment, all new users will be allocated accordingly from then on. However, all users that entered your experiment before the change will be bucketed into the same variation they entered previously, altering the results and making it difficult to interpret the conversion rate. For this reason, we recommend that you do not change individual traffic allocation to a single variation.