Describe a failure and a success

Questions

1. Tell me about a time you failed (or something didn’t go as planned). What happened, what did you learn, and what would you do differently?
2. Tell me about a time you were successful. What was your specific contribution and what was the impact?

Expectations

• Use concrete examples from engineering/ML work (delivery, incident, model launch, collaboration).
• Highlight ownership, communication, and measurable outcomes.
• Include reflection: what you changed afterward.

Solution

Use a clear structure: STAR / CAR

A reliable format is STAR:

• Situation: context and stakes
• Task: your responsibility (not the team’s)
• Action: what you did, decisions you made, tradeoffs
• Result: measurable outcome + what you learned

Or CAR (Context–Action–Result) if you want to be more concise.

1) Failure story: what interviewers look for

They want:

• A real failure (not a disguised humblebrag)
• Ownership without self-blame spirals
• Specific corrective actions and lasting process change

Good failure examples (pick one)

• Shipped a model without proper offline/online parity checks → online metrics regressed.
• Underestimated data quality issues → training pipeline produced silent corruption.
• Poor stakeholder alignment → built the wrong thing / mis-scoped MVP.

What to include

• Your decision point: why you chose that path with the info you had.
• Detection and response: how you triaged, communicated, and mitigated.
• Prevention: what you changed (tests, monitoring, review checklist, rollout plan).

Concrete additions that make it strong:

• Add numbers: “CTR dropped 1.2% relative”, “p95 latency +40ms”, “2-hour incident”.
• Add a process fix: canary release, automated data validation, feature store adoption, postmortem template.

2) Success story: what interviewers look for

They want:

• Clear individual contribution and leadership (even without formal authority)
• Impact: business + technical metrics
• Sound decision-making: tradeoffs, prioritization, and execution

Good success examples

• Launched a ranking model or retrieval improvement with measurable lift.
• Reduced training cost/latency significantly.
• Built an experimentation framework or logging pipeline that unblocked multiple teams.

What to include

• Scope: why it mattered.
• Your role: design decisions, driving alignment, unblocking others.
• Outcome: A/B results, reliability improvements, developer productivity.

3) Handling follow-ups

Common follow-ups and how to answer:

• “What would you do differently?” → name 1–2 specific changes you now apply.
• “What did you learn?” → tie to a principle (e.g., ‘validate assumptions early’, ‘instrument before optimizing’).
• “How did you influence others?” → show communication cadence, docs, design reviews.

4) Quick prep checklist (so you don’t ramble)

Prepare 2 stories (failure + success), each with:

• One-sentence summary
• 3 actions you personally took
• 2 metrics of impact
• 1 lasting change you implemented

This consistently produces senior-level behavioral answers.