Design an A/B test for a search ranking change
Last updated: September 4, 2025
Quick Overview
Design an experiment to test the impact of a redesigned homepage. Include sample size calculation, metrics, and analysis plan.
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Design an experiment to test the impact of a redesigned homepage. Include sample size calculation, metrics, and analysis plan.
This analytics question from Pinterest's Take-home Project tests your ability to think critically about data. The interviewer expects you to consider confounding variables, selection bias, and the difference between correlation and causation.
What the Interviewer Expects
- Define clear success metrics aligned with business goals
- Propose a basic experimental design with control and treatment groups
- Interpret results correctly and draw reasonable conclusions
- Identify obvious confounding variables
Key Topics to Cover
How to Approach This
- Define success metrics carefully. A good metric is measurable, actionable, and aligned with business goals.
- Run experiments long enough to account for novelty effects and weekly seasonality.
- Use funnel analysis to identify where users drop off for maximum optimization impact.
- Segment results by key dimensions (platform, country, user cohort) to catch hidden patterns.
- Consider network effects and interference between treatment and control groups.
Possible Follow-up Questions
- What if the experiment shows a positive short-term effect but you suspect a negative long-term impact?
- How would you handle interference between treatment and control?
- What if you discover a bug in the logging during the experiment?
- What would you do if a stakeholder wants to end the experiment early because initial results look good?
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Browse Analytics QuestionsSample Answer
Problem Setup
To evaluate the impact of a redesigned homepage on user engagement and search ranking, we need to frame our analytical question: **Does the redesigned homepage lead to an increase in user interaction ...
Methodology
For this A/B test, we will employ a randomized controlled trial (RCT) design. We will randomly assign users to either the control group (existing homepage) or the treatment group (redesigned homepage)...