Structure it as problem, constraints, what you tried, what you decided, and what happened after launch. Spend most of the time on decisions and tradeoffs rather than on the visuals, and be explicit about which parts were yours in a team effort. Finish with the outcome measured in numbers if you have them, and one thing you would do differently.
Why interviewers ask this
This is the core of a design interview, and it is really three tests in one: can you think, can you communicate, and were you honest about your role. Interviewers hear a lot of beautiful case studies with no problem statement and no outcome. They are listening for constraints, for options you rejected and why, and for evidence that you know what happened after the launch party.
How to structure your answer
- Open with the problem and who had it, in one or two sentences.
- State the constraints: timeline, platform, tech, business goals.
- Show the options you considered and why you killed them.
- Name your specific contribution and who else was involved.
- End with measured outcomes and what you would change.
Example answer
I will take the onboarding rebuild at my last company. The problem was that 40% of new accounts never completed setup, and support tickets showed people getting stuck at the data import step. Constraints mattered: we could not change the import backend that quarter, and we had six weeks. I ran five interviews with recent signups and watched session recordings, and the pattern was that people did not know what file format to bring, so they left to go find it and never came back. We tried three directions. A wizard with progress, which tested badly because it made a five-minute job feel like twenty. A defer-and-remind flow. And what we shipped, which let people skip import entirely and explore with sample data, with import surfaced later at the moment they hit a wall. Setup completion went from 60% to 78% over two months and import tickets halved. I did the research and the interaction design; a content designer rewrote the empty states, which did as much work as my flows did.
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See how it worksFollow-up questions to expect
- Which part of that was your work and which was someone else's?
- What would you do differently if you had another six weeks?
- How did you know the interviews were telling you the truth?
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