A control group is separated from the main experiment.

• It’s a group separated from the rest of the experiment but are still included in the test.
• It’s a group included with the experiment but are still partialy separated from the experiment.
• It’s a group included with the experiment.
• It’s a group separated from the rest of the experiment.

The correct answer is: It’s a group separated from the rest of the experiment.

Explanation: At its core, a control group is set apart from the rest of an experiment. Specifically, it consists of existing comparable campaigns in an account with 50% of the traffic. Notably, Google’s experiments prioritize control and treatment groups over backward comparisons. Such a setup is pivotal in accurately gauging the efficacy of advertisements, especially when tracking key performance indicators like online buys or in-store sales through geo-based experimental methods.

Read more here: https://support.google.com/google-ads/answer/12997711