What is the role of the daily visitors and variations in A/B test planning?

• A. They determine the content quality
• B. They determine the exact outcome
• C. They determine the required sample size and test duration
• D. They determine the designer's workload

Answer: (C)

In A/B test planning, daily visitors and the size of the difference you expect between variants determine how much data you need and how long to run the test. The daily visitor rate tells you how quickly observations accumulate, so it sets how many days you’ll need to reach the required sample size. The expected difference (variation) between the control and the variant defines the minimum detectable effect; larger expected differences require fewer observations, while smaller differences require a larger sample to detect reliably. Together, they shape the test duration and the sample size needed to achieve the chosen significance level and statistical power. If traffic is high, you can finish sooner; if traffic is low, the test lasts longer. This approach ensures you gather enough evidence to判断 whether a real effect exists, rather than relying on chance.