> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lekalao.com/llms.txt
> Use this file to discover all available pages before exploring further.

# A/B tests

> Try up to five versions on a sample, and send the best one to the rest.

An A/B test sends several versions of a campaign to a **sample** of the list, waits, picks the **winner** on the criterion you chose, then sends it **to the rest** of the list, on its own.

## Switch the test on

The campaign's **Settings** tab, the **A/B test** section:

<ParamField path="Number of versions" type="2 to 5" default="2">
  Each version gets the same share of the sample.
</ParamField>

<ParamField path="Sample size" type="5 % to 80 %">
  The share of the list that receives the test, drawn at random. With 20 % of
  a list of 10,000 people and two versions: 1,000 receive A, 1,000 receive B,
  and 8,000 will receive the winner.
</ParamField>

<ParamField path="Winner decided on" type="criterion">
  * **Most unique opens**: for testing subjects. - **Most unique clicks**:
    for testing content. - **Most money earned**: for testing what sells (you
    need to [report your sales](/developers/conversions)).
</ParamField>

<ParamField path="Wait before deciding" type="5 minutes to 7 days">
  Give your readers time: 2 to 4 hours for opens, a day for money.
</ParamField>

## Writing the versions

In the **Content** tab, **Version A**, **Version B**… buttons replace the language tabs. Each version has its own **subject** and **content**; the editor, the template and the settings are shared. A field left empty falls back to the campaign's own.

<Tip>
  Change one thing at a time. Two different subjects with the same content
  teach you which subject works better; two entirely different e-mails teach
  you nothing you can use again.
</Tip>

## While the test runs

1. **Send now** sends the sample, split between the versions.
2. The scheduler checks every minute whether the wait is over.
3. The version with the best score becomes the **winner**; on a tie, the first one (A) wins.
4. The winner goes to the remaining recipients, at the same sending pace.

The **Delivery** tab repeats the test ("Both versions go to X % of the recipients…") and, once it is decided, which version won and when.

## Reading the results

In **Statistics**, the **A/B test** section shows each version with its subject, how many were sent, its opens and its clicks; the winner is marked **Winner**. In the **Outbox**, the **Version** column says what each person received.

<Note>
  A version already sent cannot be deleted, and the versions of an A/B test
  are not translated. To test in several languages, make one campaign per
  language segment.
</Note>