Which of the following is considered a best practice when creating a campaign experiment?

• Focus tests on one variable at a time and use separate tests to examine the effects of more than one change.
• After an experiment ends, evaluate performance over a timeline that includes the ramp-up period.
• When experimenting with creatives, new ads are not subject to ad approvals, so experiments can be expedited.
• Pick two or three metrics to evaluate campaign performance and determine the winner of a test.

The correct answer is:

• Focus tests on one variable at a time and use separate tests to examine the effects of more than one change.