> ## Documentation Index
> Fetch the complete documentation index at: https://www.algolia.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Declare and adopt an A/B test winner
> Apply a winning variant's configuration to your control directly from the test page.
export const AlgoliaSearch = () => ;
When you adopt an A/B test winner, Algolia applies the winning variant's settings to your live search.
You don't have to copy each setting by hand or set up your index again.
## Before you begin
You'll need:
* **Admin access** to your Algolia dashboard. Without it, you can declare a winner, but you can't promote the settings.
* **An A/B test with at least 80% completion**, based on its scheduled duration. Until then, you can't declare a winner.
* **A variant as the winner.** You can't adopt the control, so the dashboard hides this option if the control wins.
Plan for 5 to 10 minutes to adopt the settings, then 2 to 3 hours to watch the results.
## Declare A/B test winner
1. On the left sidebar, select **Search**.
2. On the [**A/B testing**](https://dashboard.algolia.com/ab-tests/overview) page, select the A/B test you want to work on.
3. On the A/B test detail page, select the variant you want as the winner and click **Declare winner**.
Declaring a winner doesn't change your indices.
You can adopt the winning settings as soon as you declare it.
## Promote settings
After you declare a winner, click **Promote settings**.
This copies the winning settings to your control.
**Adoption window:** You have 14 days to adopt the winning settings, counted from the day the test ends or you stop it.
After that, apply the settings to your index by hand.
### Confirm promotion
To confirm updating the index settings:
* If the winning variant uses the same index as the control: Enter `COPY`
* If the winning variant uses a different index as the control: Enter `UPDATE`
Click **Confirm** to proceed.
## What adoption changes
Adoption copies most settings from your winning variant to your control.
Some limits apply.
### Changed settings
* The control's index settings, updated to match the winning variant. If the variant shares the control's index, the custom search parameters change instead.
* These feature settings, toggled on or off to match the winner:
* [Dynamic Re-Ranking](/doc/guides/algolia-ai/re-ranking)
* [NeuralSearch](/doc/guides/algolia-ai)
* [Personalization](/doc/guides/personalization/classic-personalization/what-is-personalization)
* [Advanced Personalization](/doc/guides/personalization/advanced-personalization/what-is-advanced-personalization)
If the control is a [replica](/doc/guides/managing-results/refine-results/sorting/in-depth/replicas), virtual or standard, fewer settings carry over.
Algolia applies only the [index settings that replicas support](/doc/guides/managing-results/refine-results/sorting/in-depth/replicas#supported-index-settings-for-virtual-replicas).
### Unchanged settings
* **Records.** Adoption never modifies your data.
* **Synonyms and Rules.** Adoption leaves these untouched.
## Verify adoption
After promoting settings, verify the changes work as expected:
1. **Check your index settings** in the dashboard. Your control index should now show the winning variant's settings.
2. **Check your analytics** for unexpected changes over the next 2 to 3 hours.
## Revert settings
You can revert the adoption for 15 days after your A/B test ends, or after you stop it.
To revert to your previous settings:
1. Open the A/B test details page in the dashboard.
2. On the control variant, click **Revert**.
3. Confirm by entering `REVERT` and clicking **Confirm**.
The winning variant still appears as the winner, but no longer shows as promoted.
### Revert limitations
* You can't promote settings again for this A/B test after reverting.
* Reverting can only undo the settings that adoption applied.
* The limits above also apply when you revert, both the replica limits and the fixed list of feature settings.
**Need help?** If something looks wrong after you revert, contact [Algolia support](https://support.algolia.com/hc/en-us/requests/new).
## See also
* [Create and run an A/B test](/doc/guides/ab-testing/what-is-ab-testing/how-to/create-and-run-an-ab-test)
* [How to read your A/B test results](/doc/guides/ab-testing/how-to-read-your-a-b-test-results)
Declaring a winner doesn't change your indices.
You can adopt the winning settings as soon as you declare it.
## Promote settings
After you declare a winner, click **Promote settings**.
This copies the winning settings to your control.
3. Confirm by entering `REVERT` and clicking **Confirm**.
The winning variant still appears as the winner, but no longer shows as promoted.
### Revert limitations
* You can't promote settings again for this A/B test after reverting.
* Reverting can only undo the settings that adoption applied.
* The limits above also apply when you revert, both the replica limits and the fixed list of feature settings.