When planning an A/B test, which action is commonly considered essential before launching?

• A. Decide the budget after the test.
• B. Choose the variable to test.
• C. Publish the results to social media.
• D. Ignore baselines.

Answer: (B)

Choosing the variable to test is essential before you launch an A/B test because it defines what you’re actually comparing and what hypothesis you’re trying to test. By selecting the specific element to modify (for example, a headline, button color, or page layout), you create two distinct versions: a control and a treatment. This lets you measure the impact of that single change on a chosen metric (like conversion rate or click-through rate) with a clear, testable expectation. It also guides how you set up the experiment, including random assignment, sample size, duration, and how you’ll interpret results.

Other pre-launch considerations, like budgeting after the test, or publishing results before starting, aren’t part of planning a valid experiment and don’t help you isolate effects. Ignoring baselines makes it impossible to determine whether observed differences are meaningful, so having a defined baseline and the specific variable to test keeps the test interpretable and actionable.