System-managed experiments are used to A/B test changes by creating one or more
modifiable treatment campaigns that run alongside an original control campaign.
This workflow is supported for the following
[`ExperimentType`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentTypeEnum.ExperimentType.md.txt) values:

- `SEARCH_CUSTOM`: A custom experiment consisting of search campaigns.
- `DISPLAY_CUSTOM`: A custom experiment consisting of display campaigns.
- `HOTEL_CUSTOM`: A custom experiment consisting of hotel campaigns.
- `YOUTUBE_CUSTOM`: A custom experiment consisting of Video campaigns.
- `PMAX_REPLACEMENT_SHOPPING`: An experiment to test how your Shopping campaigns perform compared to Performance Max.

## Setup

The setup for system-managed experiments follows these steps:

1. Create an `Experiment`.
2. Create `ExperimentArm` resources for control and treatment.
3. Modify the `in_design_campaigns` in the treatment arms.

### 1. Create an experiment

The first step in running an experiment using the Google Ads API is to create an
[`Experiment`](https://developers.google.com/google-ads/api/reference/rpc/v26/Experiment.md.txt). This resource defines key information about the
experiment you want to run. You don't specify any of the campaigns involved in
the experiment at this step.

Here's an overview of some key fields for an `Experiment`:

- `name`: Each experiment must have a unique name.
- `description`: An optional field that you can use to reference later. Does not affect how the experiment runs.
- `suffix`: The suffix is appended to the end of the names of the treatment campaigns so you can distinguish them from the control campaign. These concepts are explained further in [step 2](https://developers.google.com/google-ads/api/docs/experiments/system-managed.md.txt#create-experiment-arms).
- `type`: What type of experiment to run. For system-managed experiments, use `SEARCH_CUSTOM`, `DISPLAY_CUSTOM`, `HOTEL_CUSTOM`, `YOUTUBE_CUSTOM`, or `PMAX_REPLACEMENT_SHOPPING`.
- `status`: When creating an experiment, set this field to `SETUP`. Later on, once you begin the experiment, this field lets you check the current status.
- `start_date` and `end_date`: Specify when the experiment should start and end.
- `sync_enabled`: Disabled by default. If set to `true`, changes made to the original campaign while your experiment is running are automatically copied to the experiment campaign. For more details, see [campaign sync in the
  Google Ads Help Center](https://support.google.com/google-ads/answer/10575537).


### Java

```java
private String createExperimentResource(GoogleAdsClient googleAdsClient, long customerId) {
  ExperimentOperation operation =
      ExperimentOperation.newBuilder()
          .setCreate(
              Experiment.newBuilder()
                  // Name must be unique.
                  .setName("Example Experiment #" + getPrintableDateTime())
                  // We specify SEARCH_CUSTOM to create a standard search campaign experiment.
                  // This type uses a standard draft-based workflow where the system automatically
                  // creates a draft/in-design campaign for the treatment arm.
                  .setType(ExperimentType.SEARCH_CUSTOM)
                  .setSuffix("[experiment]")
                  .setStatus(ExperimentStatus.SETUP)
                  .build())
          .build();

  try (ExperimentServiceClient experimentServiceClient =
      googleAdsClient.getLatestVersion().createExperimentServiceClient()) {
    MutateExperimentsResponse response =
        experimentServiceClient.mutateExperiments(
            Long.toString(customerId), ImmutableList.of(operation));
    String experiment = response.getResults(0).getResourceName();
    System.out.printf("Created experiment with resource name '%s'%n", experiment);
    return experiment;
  }
}

      
```

### C#

```c#
private static string CreateExperimentResource(GoogleAdsClient client, long customerId)
{
    // Get the ExperimentService.
    ExperimentServiceClient experimentService = client.GetService(
        Services.V26.ExperimentService);

    // Creates the experiment.
    Experiment experiment = new Experiment()
    {
        // Name must be unique.
        Name = $"Example Experiment #{ExampleUtilities.GetRandomString()}",
        // We specify SearchCustom to create a standard search campaign experiment.
        // This type uses a standard draft-based workflow where the system automatically
        // creates a draft/in-design campaign for the treatment arm.
        Type = ExperimentType.SearchCustom,
        Suffix = "[experiment]",
        Status = ExperimentStatus.Setup
    };

    // Creates the operation.
    ExperimentOperation operation = new ExperimentOperation()
    {
        Create = experiment
    };

    // Makes the API call.
    MutateExperimentsResponse response = experimentService.MutateExperiments(
        customerId.ToString(), new[] { operation });

    // Displays the result.
    string experimentResourceName = response.Results.First().ResourceName;

    Console.WriteLine($"Created experiment with resource name " +
        $"'{experimentResourceName}'.");
    return experimentResourceName;
}
      
```

### PHP

```php
private static function createExperimentResource(
    ExperimentServiceClient $experimentServiceClient,
    int $customerId
): string {
    // Creates an experiment and its operation.
    $experiment = new Experiment(
        [
        // Name must be unique.
        'name' => 'Example Experiment #' . Helper::getPrintableDatetime(),
        'type' => ExperimentType::SEARCH_CUSTOM,
        'suffix' => '[experiment]',
        'status' => ExperimentStatus::SETUP
        ]
    );
    $experimentOperation = new ExperimentOperation(['create' => $experiment]);

    // Issues a request to create the experiment.
    $response = $experimentServiceClient->mutateExperiments(
        MutateExperimentsRequest::build($customerId, [$experimentOperation])
    );
    $experimentResourceName = $response->getResults()[0]->getResourceName();
    print "Created experiment with resource name '$experimentResourceName'" . PHP_EOL;

    return $experimentResourceName;
}
      
```

### Python

```python
def create_experiment_resource(
    client: GoogleAdsClient, customer_id: str
) -> str:
    """Creates a new experiment resource.

    Args:
        client: an initialized GoogleAdsClient instance.
        customer_id: a client customer ID.

    Returns:
        the resource name for the new experiment.
    """
    experiment_operation: ExperimentOperation = client.get_type(
        "ExperimentOperation"
    )
    experiment: Experiment = experiment_operation.create

    experiment.name = f"Example Experiment #{uuid.uuid4()}"
    # We specify SEARCH_CUSTOM to create a standard search campaign experiment.
    # This type uses a standard draft-based workflow where the system automatically
    # creates a draft/in-design campaign for the treatment arm.
    experiment.type_ = client.enums.ExperimentTypeEnum.SEARCH_CUSTOM
    experiment.suffix = "[experiment]"
    experiment.status = client.enums.ExperimentStatusEnum.SETUP

    experiment_service: ExperimentServiceClient = client.get_service(
        "ExperimentService"
    )
    response: MutateExperimentsResponse = experiment_service.mutate_experiments(
        customer_id=customer_id, operations=[experiment_operation]
    )

    experiment_resource_name: str = response.results[0].resource_name
    print(f"Created experiment with resource name {experiment_resource_name}")

    return experiment_resource_name
      
```

### Ruby

```ruby
def create_experiment_resource(client, customer_id)
  operation = client.operation.create_resource.experiment do |e|
    # Name must be unique.
    e.name = "Example Experiment #{(Time.new.to_f * 1000).to_i}"
    # We specify SEARCH_CUSTOM to create a standard search campaign experiment.
    # This type uses a standard draft-based workflow where the system automatically
    # creates a draft/in-design campaign for the treatment arm.
    e.type = :SEARCH_CUSTOM
    e.suffix = '[experiment]'
    e.status = :SETUP
  end

  response = client.service.experiment.mutate_experiments(
    customer_id: customer_id,
    operations: [operation],
  )

  experiment = response.results.first.resource_name
  puts "Created experiment with resource name #{experiment}."

  experiment
end
      
```

### Perl

```perl
sub create_experiment_resource {
  my ($api_client, $customer_id) = @_;

  my $experiment = Google::Ads::GoogleAds::V26::Resources::Experiment->new({
    # Name must be unique.
    name   => "Example Experiment #" . uniqid(),
    type   => SEARCH_CUSTOM,
    suffix => "[experiment]",
    status => SETUP
  });

  my $operation =
    Google::Ads::GoogleAds::V26::Services::ExperimentService::ExperimentOperation
    ->new({
      create => $experiment
    });

  my $response = $api_client->ExperimentService()->mutate({
      customerId => $customer_id,
      operations => [$operation]});

  my $resource_name = $response->{results}[0]{resourceName};
  printf "Created experiment with resource name '%s'.\n", $resource_name;
  return $resource_name;
}
      
```

### curl

> [!NOTE]
> **Note:** While a direct REST code sample for this step isn't provided here, you can achieve this using a manual REST request.   
>
> Refer to the Google Ads API REST interface documentation and the method-specific reference pages. You will need to construct the JSON payload based on the proto definitions.   
>
> Key Resources:
>
> - [Using REST](https://developers.google.com/google-ads/api/rest/overview.md.txt)
> - [REST Interface Structure](https://developers.google.com/google-ads/api/rest/design/overview.md.txt)
> - [JSON Field Mappings](https://developers.google.com/google-ads/api/rest/design/json-mappings.md.txt)
> - Consult the [REST API Reference](https://developers.google.com/google-ads/api/reference/rpc/latest/overview) for the specific service and method.

<br />

### 2. Create experiment arms

Next, create [`ExperimentArm`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentArm.md.txt) resources to define the control
and treatment groups for the experiment. All arms must be created in a single
request.

Each experiment must have exactly one control arm and one or more treatment
arms. The control arm identifies the base campaign for comparison, and each
treatment arm results in a new campaign where you can make changes to test.

You must also specify `traffic_split`, which is the percentage of traffic
directed to each arm. The sum of traffic splits across all arms must be 100.


### Java

```java
private String createExperimentArms(
    GoogleAdsClient googleAdsClient, long customerId, long campaignId, String experiment) {
  List<ExperimentArmOperation> operations = new ArrayList<>();
  operations.add(
      ExperimentArmOperation.newBuilder()
          .setCreate(
              // The "control" arm references an already-existing campaign.
              ExperimentArm.newBuilder()
                  .setControl(true)
                  .addCampaigns(ResourceNames.campaign(customerId, campaignId))
                  .setExperiment(experiment)
                  .setName("control arm")
                  .setTrafficSplit(40)
                  .build())
          .build());
  operations.add(
      ExperimentArmOperation.newBuilder()
          .setCreate(
              // In standard campaign experiments, creating the treatment arm automatically
              // generates a draft campaign that you can modify before starting the experiment.
              ExperimentArm.newBuilder()
                  .setControl(false)
                  .setExperiment(experiment)
                  .setName("experiment arm")
                  .setTrafficSplit(60)
                  .build())
          .build());

  try (ExperimentArmServiceClient experimentArmServiceClient =
      googleAdsClient.getLatestVersion().createExperimentArmServiceClient()) {
    // Constructs the mutate request.
    MutateExperimentArmsRequest mutateRequest =
        MutateExperimentArmsRequest.newBuilder()
            .setCustomerId(Long.toString(customerId))
            .addAllOperations(operations)
            // We want to fetch the draft campaign IDs from the treatment arm, so the easiest way
            // to do that is to have the response return the newly created entities.
            .setResponseContentType(ResponseContentType.MUTABLE_RESOURCE)
            .build();

    // Sends the mutate request.
    MutateExperimentArmsResponse response =
        experimentArmServiceClient.mutateExperimentArms(mutateRequest);

    // Results always return in the order that you specify them in the request. Since we created
    // the treatment arm last, it will be the last result.  If you don't remember which arm is the
    // treatment arm, you can always filter the query in the next section with
    // `experiment_arm.control = false`.
    MutateExperimentArmResult controlArmResult = response.getResults(0);
    MutateExperimentArmResult treatmentArmResult =
        response.getResults(response.getResultsCount() - 1);

    System.out.printf(
        "Created control arm with resource name '%s'%n", controlArmResult.getResourceName());
    System.out.printf(
        "Created treatment arm with resource name '%s'%n", treatmentArmResult.getResourceName());

    return treatmentArmResult.getExperimentArm().getInDesignCampaigns(0);
  }
}

      
```

### C#

```c#
private static (MutateExperimentArmResult, MutateExperimentArmResult)
    CreateExperimentArms(GoogleAdsClient client, long customerId, long baseCampaignId,
        string experimentResourceName)
{
    // Get the ExperimentArmService.
    ExperimentArmServiceClient experimentService = client.GetService(
        Services.V26.ExperimentArmService);

    // Create the control arm. The control arm references an already-existing campaign.
    ExperimentArmOperation controlArmOperation = new ExperimentArmOperation()
    {
        Create = new ExperimentArm()
        {
            Control = true,
            Campaigns = {
                ResourceNames.Campaign(customerId, baseCampaignId)
            },
            Experiment = experimentResourceName,
            Name = "Control Arm",
            TrafficSplit = 40
        }
    };

    // Create the non-control arm.
    // In standard campaign experiments, creating the treatment arm automatically
    // generates a draft campaign that you can modify before starting the experiment.
    ExperimentArmOperation treatmentArmOperation = new ExperimentArmOperation()
    {
        Create = new ExperimentArm()
        {
            Control = false,
            Experiment = experimentResourceName,
            Name = "Experiment Arm",
            TrafficSplit = 60
        }
    };

    // We want to fetch the draft campaign IDs from the treatment arm, so the
    // easiest way to do that is to have the response return the newly created
    // entities.
    MutateExperimentArmsRequest request = new MutateExperimentArmsRequest
    {
        CustomerId = customerId.ToString(),
        Operations = { controlArmOperation, treatmentArmOperation },
        ResponseContentType = ResponseContentType.MutableResource
    };

    MutateExperimentArmsResponse response = experimentService.MutateExperimentArms(
        request
    );

    // Results always return in the order that you specify them in the request.
    // Since we created the treatment arm last, it will be the last result.
    MutateExperimentArmResult controlArm = response.Results.First();
    MutateExperimentArmResult treatmentArm = response.Results.Last();

    Console.WriteLine($"Created control arm with resource name " +
        $"'{controlArm.ResourceName}'.");
    Console.WriteLine($"Created treatment arm with resource name" +
      $" '{treatmentArm.ResourceName}'.");
    return (controlArm, treatmentArm);
}
      
```

### PHP

```php
private static function createExperimentArms(
    GoogleAdsClient $googleAdsClient,
    int $customerId,
    int $campaignId,
    string $experimentResourceName
): string {
    $operations = [];
    $experimentArm1 = new ExperimentArm(
        [
        // The "control" arm references an already-existing campaign.
        'control' => true,
        'campaigns' => [ResourceNames::forCampaign($customerId, $campaignId)],
        'experiment' => $experimentResourceName,
        'name' => 'control arm',
        'traffic_split' => 40
        ]
    );
    $operations[] = new ExperimentArmOperation(['create' => $experimentArm1]);
    $experimentArm2 = new ExperimentArm(
        [
        // The non-"control" arm, also called a "treatment" arm, will automatically
        // generate draft campaigns that you can modify before starting the
        // experiment.
        'control' => false,
        'experiment' => $experimentResourceName,
        'name' => 'experiment arm',
        'traffic_split' => 60
        ]
    );
    $operations[] = new ExperimentArmOperation(['create' => $experimentArm2]);

    // Issues a request to create the experiment arms.
    $experimentArmServiceClient = $googleAdsClient->getExperimentArmServiceClient();
    $response = $experimentArmServiceClient->mutateExperimentArms(
        MutateExperimentArmsRequest::build($customerId, $operations)
            // We want to fetch the draft campaign IDs from the treatment arm, so the easiest
            // way to do that is to have the response return the newly created entities.
            ->setResponseContentType(ResponseContentType::MUTABLE_RESOURCE)
    );
    // Results always return in the order that you specify them in the request.
    // Since we created the treatment arm last, it will be the last result.
    $controlArmResourceName = $response->getResults()[0]->getResourceName();
    $treatmentArm = $response->getResults()[count($operations) - 1];
    print "Created control arm with resource name '$controlArmResourceName'" . PHP_EOL;
    print "Created treatment arm with resource name '{$treatmentArm->getResourceName()}'"
        . PHP_EOL;

    return $treatmentArm->getExperimentArm()->getInDesignCampaigns()[0];
}
      
```

### Python

```python
def create_experiment_arms(
    client: GoogleAdsClient,
    customer_id: str,
    base_campaign_id: str,
    experiment: str,
) -> str:
    """Creates a control and treatment experiment arms.

    Args:
        client: an initialized GoogleAdsClient instance.
        customer_id: a client customer ID.
        base_campaign_id: the campaign ID to associate with the control arm of
          the experiment.
        experiment: the resource name for an experiment.

    Returns:
        the resource name for the new treatment experiment arm.
    """
    operations: List[ExperimentArmOperation] = []

    campaign_service: CampaignServiceClient = client.get_service(
        "CampaignService"
    )

    # The "control" arm references an already-existing campaign.
    operation_1: ExperimentArmOperation = client.get_type(
        "ExperimentArmOperation"
    )
    exa_1: ExperimentArm = operation_1.create
    exa_1.control = True
    exa_1.campaigns.append(
        campaign_service.campaign_path(customer_id, base_campaign_id)
    )
    exa_1.experiment = experiment
    exa_1.name = "control arm"
    exa_1.traffic_split = 40
    operations.append(operation_1)

    # In standard campaign experiments, creating the treatment arm automatically
    # generates a draft campaign that you can modify before starting the experiment.
    operation_2: ExperimentArmOperation = client.get_type(
        "ExperimentArmOperation"
    )
    exa_2: ExperimentArm = operation_2.create
    exa_2.control = False
    exa_2.experiment = experiment
    exa_2.name = "experiment arm"
    exa_2.traffic_split = 60
    operations.append(operation_2)

    experiment_arm_service: ExperimentArmServiceClient = client.get_service(
        "ExperimentArmService"
    )
    request: MutateExperimentArmsRequest = client.get_type(
        "MutateExperimentArmsRequest"
    )
    request.customer_id = customer_id
    request.operations = operations
    # We want to fetch the draft campaign IDs from the treatment arm, so the
    # easiest way to do that is to have the response return the newly created
    # entities.
    request.response_content_type = (
        client.enums.ResponseContentTypeEnum.MUTABLE_RESOURCE
    )
    response: MutateExperimentArmsResponse = (
        experiment_arm_service.mutate_experiment_arms(request=request)
    )

    # Results always return in the order that you specify them in the request.
    # Since we created the treatment arm second, it will be the second result.
    control_arm_result: Any = response.results[0]
    treatment_arm_result: Any = response.results[1]

    print(
        f"Created control arm with resource name {control_arm_result.resource_name}"
    )
    print(
        f"Created treatment arm with resource name {treatment_arm_result.resource_name}"
    )

    return treatment_arm_result.experiment_arm.in_design_campaigns[0]
      
```

### Ruby

```ruby
def create_experiment_arms(client, customer_id, base_campaign_id, experiment)
  operations = []
  operations << client.operation.create_resource.experiment_arm do |ea|
    # The "control" arm references an already-existing campaign.
    ea.control = true
    ea.campaigns << client.path.campaign(customer_id, base_campaign_id)
    ea.experiment = experiment
    ea.name = 'control arm'
    ea.traffic_split = 40
  end
  operations << client.operation.create_resource.experiment_arm do |ea|
    # In standard campaign experiments, creating the treatment arm automatically
    # generates a draft campaign that you can modify before starting the
    # experiment.
    ea.control = false
    ea.experiment = experiment
    ea.name = 'experiment arm'
    ea.traffic_split = 60
  end

  response = client.service.experiment_arm.mutate_experiment_arms(
    customer_id: customer_id,
    operations: operations,
    # We want to fetch the draft campaign IDs from the treatment arm, so the
    # easiest way to do that is to have the response return the newly created
    # entities.
    response_content_type: :MUTABLE_RESOURCE,
  )

  # Results always return in the order that you specify them in the request.
  # Since we created the treatment arm second, it will be the second result.
  control_arm_result = response.results.first
  treatment_arm_result = response.results.last

  puts "Created control arm with resource name #{control_arm_result.resource_name}."
  puts "Created treatment arm with resource name #{treatment_arm_result.resource_name}."

  treatment_arm_result.experiment_arm.in_design_campaigns.first
end
      
```

### Perl

```perl
sub create_experiment_arms {
  my ($api_client, $customer_id, $base_campaign_id, $experiment) = @_;

  my $operations = [];
  push @$operations,
    Google::Ads::GoogleAds::V26::Services::ExperimentArmService::ExperimentArmOperation
    ->new({
      create => Google::Ads::GoogleAds::V26::Resources::ExperimentArm->new({
          # The "control" arm references an already-existing campaign.
          control   => "true",
          campaigns => [
            Google::Ads::GoogleAds::V26::Utils::ResourceNames::campaign(
              $customer_id, $base_campaign_id
            )
          ],
          experiment   => $experiment,
          name         => "control arm",
          trafficSplit => 40
        })});

  push @$operations,
    Google::Ads::GoogleAds::V26::Services::ExperimentArmService::ExperimentArmOperation
    ->new({
      create => Google::Ads::GoogleAds::V26::Resources::ExperimentArm->new({
          # The non-"control" arm, also called a "treatment" arm, will automatically
          # generate draft campaigns that you can modify before starting the
          # experiment.
          control      => "false",
          experiment   => $experiment,
          name         => "experiment arm",
          trafficSplit => 60
        })});

  my $response = $api_client->ExperimentArmService()->mutate({
    customerId => $customer_id,
    operations => $operations,
    # We want to fetch the draft campaign IDs from the treatment arm, so the
    # easiest way to do that is to have the response return the newly created
    # entities.
    responseContentType => MUTABLE_RESOURCE
  });

  # Results always return in the order that you specify them in the request.
  # Since we created the treatment arm last, it will be the last result.
  my $control_arm_result   = $response->{results}[0];
  my $treatment_arm_result = $response->{results}[1];

  printf "Created control arm with resource name '%s'.\n",
    $control_arm_result->{resourceName};
  printf "Created treatment arm with resource name '%s'.\n",
    $treatment_arm_result->{resourceName};
  return $treatment_arm_result->{experimentArm}{inDesignCampaigns}[0];
}
      
```

### curl

> [!NOTE]
> **Note:** While a direct REST code sample for this step isn't provided here, you can achieve this using a manual REST request.   
>
> Refer to the Google Ads API REST interface documentation and the method-specific reference pages. You will need to construct the JSON payload based on the proto definitions.   
>
> Key Resources:
>
> - [Using REST](https://developers.google.com/google-ads/api/rest/overview.md.txt)
> - [REST Interface Structure](https://developers.google.com/google-ads/api/rest/design/overview.md.txt)
> - [JSON Field Mappings](https://developers.google.com/google-ads/api/rest/design/json-mappings.md.txt)
> - Consult the [REST API Reference](https://developers.google.com/google-ads/api/reference/rpc/latest/overview) for the specific service and method.

<br />

A few key points:

- Exactly one arm must have `control` set to `true`.
- The `traffic_split` must add up to 100 across all arms.
- The control arm must specify exactly one campaign in its `campaigns` field.

> [!NOTE]
> **Note:** You cannot use [partial failure](https://developers.google.com/google-ads/api/docs/best-practices/partial-failures.md.txt) when creating experiment arms.

### 3. Modify treatment campaigns

When you create a treatment arm (where `control` is `false`), the API
automatically creates a draft campaign based on the control campaign and
populates its resource name in the `in_design_campaigns` field of the treatment
arm. You can treat these in-design campaigns as regular campaigns and modify
them with the changes you want to test. The control campaign won't be affected.
These changes are materialized into a real, servable campaign when you schedule
the experiment.

At least one change must be made to an in-design campaign before you can
schedule the experiment.

To retrieve the `in_design_campaigns` for a treatment arm, you can query
`GoogleAdsService`:

```sql
SELECT experiment_arm.in_design_campaigns
FROM experiment_arm
WHERE experiment_arm.resource_name = 'TREATMENT_ARM_RESOURCE_NAME'
PARAMETERS include_drafts = true
```

> [!TIP]
> **Tip:** Draft and in-design campaigns are only returned when you include `PARAMETERS include_drafts = true` in your [GAQL query](https://developers.google.com/google-ads/api/docs/query/structure.md.txt#parameters).

## Schedule the experiment

After creating the experiment and arms and modifying the treatment draft
campaigns, you can schedule the experiment using
[`ExperimentService.ScheduleExperiment`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentService/ScheduleExperiment.md.txt). This is an
asynchronous operation that materializes the in-design campaigns into actual
campaigns, ready to serve once the experiment's `start_date` arrives. See
[Asynchronous errors](https://developers.google.com/google-ads/api/docs/experiments/async-errors.md.txt) for details on handling long-running
operations.

## Report on the experiment

Once the experiment is running, you can query for metrics to compare
performance. See the [Reporting guide](https://developers.google.com/google-ads/api/docs/experiments/reporting.md.txt) for details.

## Graduate, promote, or end the experiment

After letting the experiment run for a sufficient time, you can choose to end,
promote, or graduate it using [`ExperimentService`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentService.md.txt).

- **End** : If you want to stop the experiment without applying changes, use [`EndExperiment`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentService/EndExperiment.md.txt). The treatment campaigns stop serving, but are not removed. This is a synchronous operation.
- **Promote** : If you are satisfied with the treatment arm's performance and want to incorporate the changes into your original campaign, use [`PromoteExperiment`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentService/PromoteExperiment.md.txt). This copies changes from the treatment arm to the control campaign and stops the treatment arm from serving. This is an asynchronous operation; see [Asynchronous
  errors](https://developers.google.com/google-ads/api/docs/experiments/async-errors) for details. Note: Experiments of type `PMAX_REPLACEMENT_SHOPPING` cannot be promoted.
- **Graduate** : If you liked the changes, but want them to exist separately from the original campaign, use [`GraduateExperiment`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentService/GraduateExperiment.md.txt). This converts the treatment campaign into a standard, independent campaign that continues to serve outside the context of the experiment. The control campaign is not modified. This is a synchronous operation.

## Type-specific requirements

**`PMAX_REPLACEMENT_SHOPPING`**:

- Requires exactly two arms (one control, one treatment).
- The control arm must specify one Shopping campaign in its `campaigns` field.
- For the treatment arm, you have two options for setting up the Performance Max campaign:
  - To create a *new* PMax campaign: Leave the treatment arm's `campaigns` field empty. The API automatically creates an in-design campaign based on the control Shopping campaign, as described in [Step
    3](https://developers.google.com/google-ads/api/docs/experiments/system-managed#modify-treatment-campaigns).
  - To use an *existing* PMax campaign: Specify the resource name of the PMax campaign in the treatment arm's `campaigns` field. If you select this option, no in-design campaign is created, and you can skip [Step 3](https://developers.google.com/google-ads/api/docs/experiments/system-managed.md.txt#modify-treatment-campaigns).
- We recommend discarding the first 7 days of statistics from your evaluation to give the campaign time to finish its ramp-up and learning phase.
- Cannot be promoted.

**`YOUTUBE_CUSTOM`**:

- Supports a maximum of 10 arms.
- To test assets, set [`asset_testing_info`](https://developers.google.com/google-ads/api/reference/rpc/v26/ExperimentArm.md.txt#asset_testing_info) on the experiment arm.