Once you've created an experiment, you need to create multiple experiment arms in order to give the experiment more information about what exactly you're testing.
Experiment arms
The ExperimentArm represents one part of the
comparison you're performing for the experiment. All experiments must always
have exactly one control arm. This arm is an existing campaign that forms
the basis against which you compare the other arm.
The other arms are called treatment arms, and in these arms you make changes to the campaign before beginning the experiment.
The ExperimentArm also contains the traffic_split setting. This lets you
specify the percentage of traffic that is directed to each arm of the
experiment. Each arm must specify a traffic split, and the sum of traffic split
values in all arms must add up to 100.
Because of this traffic split restriction, all experiment arms must be created in the same request.
Code example
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(
// The non-"control" arm, also called a "treatment" arm, will automatically
// generate draft campaigns 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#
/// <summary>
/// Creates the experiment arms.
/// </summary>
/// <param name="client">The Google Ads client.</param>
/// <param name="customerId">The customer ID for which the call is made.</param>
/// <param name="baseCampaignId">ID of the campaign for which the control arm is
/// created.</param>
/// <param name="experimentResourceName">Resource name of the experiment.</param>
/// <returns>The control and treatment arms.</returns>
private static (MutateExperimentArmResult, MutateExperimentArmResult)
CreateExperimentArms(GoogleAdsClient client, long customerId, long baseCampaignId,
string experimentResourceName)
{
// Get the ExperimentArmService.
ExperimentArmServiceClient experimentService = client.GetService(
Services.V15.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. The non-"control" arm, also called a "treatment" arm,
// will automatically generate draft campaigns 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
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
def create_experiment_arms(client, customer_id, base_campaign_id, experiment):
"""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 = []
campaign_service = client.get_service("CampaignService")
# The "control" arm references an already-existing campaign.
operation_1 = client.get_type("ExperimentArmOperation")
exa_1 = 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)
# The non-"control" arm, also called a "treatment" arm, will automatically
# generate draft campaigns that you can modify before starting the
# experiment.
operation_2 = client.get_type("ExperimentArmOperation")
exa_2 = 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 = client.get_service("ExperimentArmService")
request = 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 = 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 = response.results[0]
treatment_arm_result = 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
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|
# The non-"control" arm, also called a "treatment" arm, will automatically
# generate draft campaigns 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 last, it will be the last 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
sub create_experiment_arms {
my ($api_client, $customer_id, $base_campaign_id, $experiment) = @_;
my $operations = [];
push @$operations,
Google::Ads::GoogleAds::V15::Services::ExperimentArmService::ExperimentArmOperation
->new({
create => Google::Ads::GoogleAds::V15::Resources::ExperimentArm->new({
# The "control" arm references an already-existing campaign.
control => "true",
campaigns => [
Google::Ads::GoogleAds::V15::Utils::ResourceNames::campaign(
$customer_id, $base_campaign_id
)
],
experiment => $experiment,
name => "control arm",
trafficSplit => 40
})});
push @$operations,
Google::Ads::GoogleAds::V15::Services::ExperimentArmService::ExperimentArmOperation
->new({
create => Google::Ads::GoogleAds::V15::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];
}
A few key points about the example above:
- The
nameof each arm must be unique within theExperiment. - The
traffic_splitmust add up to 100 across all arms. Exactly one arm must have
controlset totrue; all other arms must have it set tofalse.Only the control arm specifies a
campaignsarray, which holds only one campaign.
Treatment arms
Once you've created all the experiment arms, the treatment arms—the arms
where control is set to false—automatically populate their
in_design_campaigns field. You can retrieve the field from the API response
by setting the response content type to MUTABLE_RESOURCE like in the code
example. You can also fetch it through a
GoogleAdsService query:
SELECT experiment_arm.in_design_campaigns
FROM experiment_arm
WHERE experiment_arm.resource_name = "TREATMENT_ARM_RESOURCE_NAME"
In-design campaigns
You can treat these in-design campaigns as regular campaigns. Make whatever changes you want to test in your experiment to these campaigns; the control campaign won't be affected. Once you schedule the experiment, these changes are materialized into a real campaign that can serve ads.
These in-design campaigns are technically draft campaigns. If you want to
find them in GoogleAdsService, add the include_drafts=true
parameter to the query.
At least one change must be made to the in-design campaign before you can schedule the experiment.