> ## Documentation Index
> Fetch the complete documentation index at: https://launchdarkly-preview.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Variation reassignment

> This topic explains how LaunchDarkly reassigns contexts to flag variations when you change or increase traffic in an experiment.

> For the complete documentation index, see [llms.txt](/llms.txt). For the full documentation snapshot, see [llms-full.txt](/llms-full.txt).

## Overview

This topic explains how LaunchDarkly reassigns contexts to flag variations when you change or increase traffic in an experiment.

When you make [certain edits to an experiment](/home/experimentation/edit-archive#edit-experiments), such as adding additional metrics or increasing traffic, LaunchDarkly creates a new experiment iteration. By default, LaunchDarkly reshuffles experiment traffic when you start a new iteration to help keep traffic balanced between variations.

If you want to keep contexts assigned to their original variation, you can disable variation reassignment for your experiment. You may want to do this when it's important to minimize disruption to the end-user experience, such as when different variations display different versions of navigation menus or other significant user interface (UI) elements.

## Disable variation reassignment

To disable variation reassignment for a new or existing experiment:

1. Navigate to the experiment's **Design** tab.
2. In the "Audience allocation" section, click **Advanced**.
3. Check the **Prevent variation reassignment when traffic increases** checkbox.

<Warning title="Traffic will be assigned to new variations if you stop an experiment">
  Checking the **Prevent variation reassignment when traffic increases** checkbox prevents variation reassignment only if you make changes to an experiment using the experiment's **Edit design** button.

  If you use the **Stop** button instead, LaunchDarkly will always reshuffle traffic into new variations when you start a new iteration, whether or not this box is checked.
</Warning>

### Example of an experiment with variation reassignment disabled

Here is an example of running an experiment with variation reassignment disabled: you add an experiment to a flag with three variations: A, B, and C. You roll out the three variations to 6% of contexts, while the remaining 94% receives the control, variation A. The control traffic is not part of the experiment nor its analysis.

Here is a visualization of the starting traffic allocation, with the control group on the right:

<Frame caption="An experiment audience with 6% in the experiment and 94% in the control group.">
  ![An experiment audience with 6% in the experiment and 94% in the control group.](https://files.buildwithfern.com/https://launchdarkly.docs.buildwithfern.com/docs/ab9cb3de7f54c15781240e376e9624ba69596145947a9aa8071cc942fe17b2b2/assets/images/__not_from_LD_app_UI/experiment-allocation-six-percent.png)
</Frame>

Next, you ramp up your experiment to 30% of traffic. This creates a new iteration of the experiment. In the new iteration, the 6% that were receiving variations A, B, and C, continue to receive those variations, but are no longer included in the experiment nor its analysis. New traffic is used for the 30% allocated to the experiment.

Here is an example of the modified allocation, with the control group on the right and the original experiment audience on the left:

<Frame caption="An experiment audience with 6% no longer in the experiment, 30% in the experiment, and 64% in the control group.">
  ![An experiment audience with 6% no longer in the experiment, 30% in the experiment, and 64% in the control group.](https://files.buildwithfern.com/https://launchdarkly.docs.buildwithfern.com/docs/93185802c4d75ae4c0ff01c39302b71d52fe88252cce897ae824ea9dd5eb2c4e/assets/images/__not_from_LD_app_UI/experiment-allocation-thirty-percent-no-reshuffle.png)
</Frame>
