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Amazon·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Amazon data engineer interview with a customer LTV question. Pretty light on details but the core problem was interesting enough to think through.

Questions Asked (1)

Q1

How would you calculate Customer Lifetime Value (LTV)?

Product Analytics & MetricsData Modeling
Author's notes

I started with the basic formula and then tried to layer in things like churn rate, average order value, purchase frequency.

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AI HintsAI Generated

Suggested Approach

Start by defining LTV clearly and explaining its importance for Amazon's subscription and retail businesses. Then walk through the standard formula (ARPU × gross margin × average lifespan) and discuss how to compute each component, including data sources and assumptions. Finally, mention advanced approaches like cohort analysis or predictive modeling, and tie it back to engineering considerations such as data pipelines and scalability.

Pro tip: Emphasize that LTV should be calculated on a gross margin basis, not revenue, and that for Amazon, incorporating retention curves and discount rates makes the metric more actionable for decision-making.

1. Define LTV and its business context

Explain what LTV represents and why it matters for Amazon (e.g., evaluating customer acquisition cost, guiding marketing spend, and assessing long-term value).

2. Choose the right formula and components

Present the standard formula: LTV = ARPU × gross margin × average customer lifespan. Discuss how to compute ARPU (average revenue per user), gross margin, and lifespan (using churn or retention rates).

3. Identify data sources and engineering requirements

Describe the data needed (transaction logs, subscription data, customer profiles) and how to build scalable pipelines to compute LTV, considering batch vs. streaming and data quality.

4. Handle complexities and advanced methods

Mention cohort-based analysis, predictive modeling (e.g., BG/NBD, survival analysis), and adjusting for discount rates or seasonality to improve accuracy.

5. Validate and operationalize the metric

Explain how to validate the LTV calculation (e.g., backtesting, sensitivity analysis) and integrate it into dashboards or decision systems for ongoing use.

Key Points to Mention

  • Definition of LTV and its role in unit economics (e.g., LTV:CAC ratio)
  • Formula components: ARPU, gross margin, and average customer lifespan
  • Use of cohort analysis and retention curves to estimate lifespan
  • Data engineering considerations: data sources, ETL, scalability, and real-time vs. batch processing
  • Advanced predictive models (e.g., BG/NBD, survival analysis) and their trade-offs
  • Adjustments for discount rates, seasonality, and customer segmentation

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