Test and launch your experiment

After you’ve designed your experiment and configured its delivery, you’re ready to test your experiment. Then, if all goes well, it’s time to launch it.

On the Experiment Overview page, review the Design and Delivery cards. Make sure you set everything the way you planned it. Then click Test Instrumentation to send the experiment’s variants to the testers you designated when you configured the experiment's delivery.

QA before rollout

Before any users view your experiment, make sure the variants you’ve developed look and function exactly the way you intended.

Since Experiment allows you to assign specific variants by user ID, device ID, or cohort, you can ensure that Amplitude serves your test devices the relevant variants when they enter your experiment.

Launch your experiment

When you’re satisfied the implementation is as you intended, click Start Experiment. In the modal that opens, you can set an end date for the experiment, if you prefer.

When the experiment is running, the button changes to read Complete Experiment. Click this button again when you reach the experiment's end date, or when the experiment hits statistical significance. At that point, you can do one of three things:

• roll out the winning variant
• roll back everything and return to a pre-experiment state, or
• continue the experiment

You can always revisit this decision after you've made it.

When your experiment ends

If you roll out your experiment to all users, Amplitude does the following:

• Sets rollout percentage to 100%
• Disables sticky bucketing (sets it to false)
• Changes the rollout weight of the variant you roll out, and 0 for all others.

If you roll out your experiment to "custom," the automatic changes listed above don't occur. Apply changes manually after confirming your rollout decision.

You can also roll out to "only the targeted users." This option helps avoid situations that generalize your experiment's results. For example, you target users in the United States, and see a 5% lift. These results don't mean that if you roll out to all users, you'd see a lift of 5%. Sometimes, you'd see a 5% lift for U.S users, and could see a -2% lift for all other users.

If you roll back your experiment, Amplitude:

• Turns the flag off
• Sets percentage rollouts to 0%

If you opt to continue running, your experiment, you can enter a new end date.

Now that you’ve rolled out your experiment, the next step is to learn from it.

Schedule your experiment

To schedule the experiment for launch at a later time, expand the Start Experiment menu, and click Schedule start. In the modal that appears, set the date and time that you want to begin the experiment.

QA after rollout

After rollout, you can track how many of your users were exposed to each variant on a daily basis. The Diagnostics card on the Experiment Overview page breaks this out for you in both chart and tabular form.

This is a useful way to QA the assignment process. If you notice that one variant is enrolling significantly more or significantly fewer users than you expected, it could mean an issue you should investigate.

If you do spot some outliers or anomalies that concern you, click Root Cause Analysis to conduct a deep dive into the potential causes. To learn more about how the Root Cause Analysis feature works, see this article in the Help Center.