How to Answer: “Tell me about a time you used data to make a decision.”
A complete guide to answering this common interview question — including what interviewers are really looking for, practical tips, and a worked example answer.
What interviewers are really asking
Show both analytical competence and business judgement. The best answers demonstrate that you can gather, interpret, and communicate data effectively — but also that you know when data is sufficient versus when you need qualitative insight too. Quantify the outcome.
Tips
- Show what data you gathered and why those metrics mattered.
- Demonstrate you considered the limitations of the data.
- Show how you communicated the insight to decision-makers.
- Quantify the outcome of the data-driven decision.
- Show you understand data's limits — what it can't tell you.
Example answer
Sample response
“We had a debate about whether to invest in a mobile app or improve our web experience. Instead of arguing instincts, I pulled six months of session data: 68% of signups came from mobile but conversion on mobile was less than a third of desktop. I ran five user interviews to understand why. The issue was our checkout flow, not the platform. We improved the mobile web checkout in four weeks rather than building a £150k app. Mobile conversion improved by 90% and we saved a quarter's engineering capacity. The data told us where to look; the qualitative told us what to actually fix.”
Adapt this to your own experience — never use any example answer verbatim.
Use the STAR method
Structure your answer as: Situation (brief context), Task (your specific responsibility), Action (what you personally did), Result (the quantified outcome). Most strong interview answers follow this pattern.
Full STAR method guide