Describe a situation where you had to evaluate an AI system that you built.
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What is this question about
Interviewers are usually testing whether you can evaluate AI systems in a disciplined way rather than treating evaluation as an afterthought or a demo. They want to see how you defined success, handled ambiguity, responded to imperfect results, and used evidence to drive product or technical decisions. At higher levels, they also look for whether your evaluation approach matched the risk and scope of the system.
Key Insights
- You should not frame evaluation as just reporting one metric. Show how you decided what to measure, what failure modes mattered, and why that evaluation was appropriate for the use case.
- Many candidates forget to explain what they did after the evaluation exposed problems. The strongest answers close the loop: findings changed the system, the launch decision, or the operating plan.
- If the AI system had meaningful uncertainty or risk, name the tradeoffs explicitly. You get more credit for showing judgment about imperfect models than for pretending the evaluation produced a simple yes or no answer.
What interviewers probe atlevel
Top Priority
A good junior answer does not stop at 'I measured it'; it shows that the evaluation changed what you did next.
Good examples
🟢The evaluation showed the model struggled with long inputs, so I changed the preprocessing, reran the test set, and confirmed the failure rate dropped on those cases.
🟢After I saw inconsistent outputs, I added a simple validation step and used the same evaluation set to check that it improved reliability before handing it off.
Bad examples
🔴The evaluation showed some weak areas, so I shared the results with my lead and moved on to the next task.
🔴We found a few errors, but since the average result was okay I left the implementation as it was.
Weak answers treat evaluation as reporting; strong answers use it to drive iteration and verify improvement.
Valuable
Example answers atlevel
Great answers
In my last internship I built a small classifier that routed support tickets into the right queue. For evaluation, I didn't just look at the overall accuracy, because some mistakes only delayed a ticket while others sent urgent issues to the wrong team. I created a labeled set from recent real tickets with help from a teammate, kept part of it separate from the examples I was using during development, and looked specifically at the urgent-ticket cases. The first version did okay overall but missed too many tickets that mentioned outages in less direct language. I updated the preprocessing and added a few targeted rules before the model step, then reran the same evaluation set and saw that urgent-ticket misses dropped a lot without hurting the rest. That gave my lead enough confidence to use it in a limited internal workflow first.
During a campus hackathon, I helped build a small app that used an AI model to suggest study plans based on a student’s classes and deadlines. To evaluate it, I asked a handful of students to try it with real schedules and then compared the suggestions against a simple checklist we made with a tutor, like whether the plan spread work out instead of stacking everything at the end. I found that the model sounded confident even when it missed obvious exam dates, so I started logging the inputs that led to bad suggestions and realized our prompts were too vague. After I tightened the questions we sent to the model and added a basic check for calendar conflicts, the recommendations became much more reliable. What I learned was that even for a small project, getting feedback from the actual people who would use it mattered more than just seeing whether the demo looked impressive.
Poor answers
I built a chatbot feature for an internal tool and evaluated it by asking it a bunch of questions I had already been using while building it. The answers were mostly clear and sounded natural, so I felt the model was performing well. I also compared it with another version and picked the one that seemed smarter overall. After that I shared the outputs with my team and we moved forward with it.
Question Timeline
See when this question was last asked and where, including any notes left by other candidates.
Late June, 2026
Mid May, 2026
This is as part of the new AI native behavioral round at meta.
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