Randomization units

Overview

This topic explains what randomization units are and how to use them in LaunchDarkly Experimentation. An experiment’s randomization unit is the context kind the experiment uses to assign traffic to each of its variations.

When you create an experiment, you will choose a randomization unit that determines both:

• which context kind the experiment will allocate traffic to different variations by, and
• which metrics you can use in the experiment.

Most experiments use the user randomization unit. This means that the experiment will sort contexts that encounter the experiment into different variations by user. You can also choose a different context kind, like device or organization.

Randomization units in metrics and experiments

To use a particular metric within an experiment, the metric and the experiment must use the same context kind as their randomization unit.

You select a metric’s randomization unit when you create it:

Later, when you create an experiment, select the same randomization unit to make the metric available to the experiment:

Like experiments, many metrics use a context kind of user as their randomization unit, but can also use other kinds depending on what the metric is measuring. To learn more, read Creating and managing metrics.

Randomization units other than “user”

In LaunchDarkly, the default context kind of user is automatically available for use in Experimentation. If you have created other context kinds, and want to use them as randomization units, you must first make them available for experiments.

Here’s how:

1. Navigate to the Contexts list.
2. Click the gear icon on the right. The context kinds list appears.
3. Click the three-dot overflow menu next to the context kind you want to edit.
4. Select Edit. The “Edit context kind” dialog appears.
5. Check the Available for experiments and guarded rollouts checkbox.
6. (Optional) Check the Set as the default for experiments and guarded rollouts checkbox if you want new experiments to default to this context kind as the randomization unit.
7. Click Save.

Randomization units and multi-contexts

If you use multi-contexts, you have options as to which context kind you want to use as a randomization unit for an experiment. Expand the section below to view an example.

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{
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  "kind": "multi",
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  "user": {
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    "key": "user-key-anna", // Anna has a unique user key
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    "name": "Anna",
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  },
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  "organization": {
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    "key": "org-key-global-health", // The org key is the same in both multi-contexts
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    "name": "Global Health Services",
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  }
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}
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{
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  "kind": "multi",
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  "user": {
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    "key": "user-key-jesse", // Jesse has a unique user key
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    "name": "Jesse",
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  },
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  "organization": {
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    "key": "org-key-global-health", // The org key is the same in both multi-contexts
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    "name": "Global Health Services",
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  }
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}