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Reddit·Machine Learning Engineer·Onsite - Behavioral / Leadership·Senior

SeniorPrefer not to say
Apr 2026

Summary

Behavioral round for an ML Engineer role at Reddit. Just one question but it was basically two questions stitched together, and I felt like I was rambling by the end.

Questions Asked (1)

Q1

Walk me through your biggest failure, including what caused it and what you took away from it, and then your biggest professional success, including your specific role in it and why it worked.

Root Cause AnalysisAdaptability & Ambiguity
Author's notes

Two-part question and I did not pace myself well at all.

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AI HintsAI Generated

Suggested Approach

Use a structured STAR format for both stories, but emphasize the failure first to show humility and learning. For the failure, focus on root cause and systemic fixes; for the success, highlight your specific technical contributions and measurable impact. Tailor both to ML engineering at Reddit by including scale, experimentation, and cross-functional collaboration.

Pro tip: Choose a failure that is significant but not disqualifying, and explicitly state what you would do differently today. For the success, quantify impact with metrics like engagement lift or latency reduction, and credit the team while clearly delineating your role.

1. Set the context briefly

For each story, spend 1-2 sentences on the project, your role, and the business goal. Avoid excessive background; focus on what matters for the lesson or impact.

2. Describe the failure and root cause

Explain what went wrong, your specific actions, and use a root cause analysis technique (e.g., 5 Whys) to identify the underlying issue. Be honest about your mistakes without being overly self-critical.

3. Share the lesson and corrective action

State what you learned and how you changed your approach. Give a concrete example of applying that lesson later to show growth.

4. Detail the success and your role

Describe the project, your specific contributions (e.g., model architecture, feature engineering, deployment), and why it worked. Use 'I' for your actions and 'we' for team efforts.

5. Quantify impact and tie to Reddit

Provide metrics (e.g., CTR lift, latency reduction, cost savings) and connect the success to Reddit's values or ML challenges (e.g., large-scale personalization, real-time inference).

Key Points to Mention

  • Root cause analysis technique (e.g., 5 Whys) to show structured problem-solving
  • Specific technical details: model type, data pipeline, deployment strategy
  • Quantifiable impact: metrics like engagement, latency, or revenue
  • Cross-functional collaboration with product, infra, or data teams
  • Adaptability: how you handled ambiguity or changing requirements
  • Lessons applied: a later project where you avoided the same failure

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