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Amazon·Product Manager·Onsite - Product Sense / Strategy·Senior

Senior
Jul 2026

Summary

Amazon PM interview with a system design and product strategy question about building a recommendation engine. Pretty open-ended, which I wasn't fully prepared for.

Questions Asked (1)

Q1

How would you design a recommendation system for Amazon, and what metrics would you use to measure whether it's working?

Product Analytics & MetricsSystem DesignProduct Strategy
Author's notes

I jumped straight into the algorithm side of things and the interviewer kind of steered me back toward the product framing.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the business objective and user context, then outline a recommendation system design that balances multiple signals (e.g., purchase history, browsing, similarity) and addresses cold start. Finally, define a metrics framework that includes offline evaluation, online A/B testing, and long-term business impact.

Pro tip: Emphasize the importance of measuring both immediate engagement metrics and long-term customer satisfaction, as Amazon prioritizes customer obsession over short-term gains. Also, mention the need to consider the trade-offs between different recommendation strategies (e.g., personalization vs. diversification).

1. Clarify Business Goals and User Needs

Ask clarifying questions to understand the primary objective (e.g., increase sales, improve customer experience) and the target user segments. This ensures the design aligns with Amazon's customer-centric approach.

2. Outline System Design

Describe the key components: data sources (user behavior, product catalog), algorithms (collaborative filtering, content-based, hybrid), and infrastructure (real-time vs. batch processing). Mention how to handle cold start and scalability.

3. Define Evaluation Metrics

Propose a mix of offline metrics (precision, recall, NDCG) and online metrics (CTR, conversion rate, revenue per user). Include business metrics (AOV, customer lifetime value) and guardrail metrics (page load time, diversity).

4. Plan Testing and Iteration

Explain how to run A/B tests to validate the system, measure impact, and iterate. Highlight the importance of statistical significance and long-term holdout groups.

5. Address Trade-offs and Risks

Discuss potential trade-offs (e.g., relevance vs. diversity, short-term vs. long-term) and risks (e.g., filter bubbles, privacy concerns). Show awareness of Amazon's scale and customer trust.

Key Points to Mention

  • Collaborative filtering and content-based filtering, and how to combine them in a hybrid approach
  • Handling cold start for new users and new items
  • Offline evaluation metrics like precision@k, recall@k, NDCG
  • Online metrics: click-through rate (CTR), conversion rate, add-to-cart rate
  • Business metrics: revenue per user, average order value (AOV), customer lifetime value (CLV)
  • A/B testing methodology and long-term impact measurement

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.