A practice prompt we wrote. No company or candidate report names it, so it carries no company tag.
How to answer
This question is about the two days after discovery: the interviewer wants to see you turn “the data is bad” into a measurement, tell the customer before the date forces it, and come out with a plan they chose.
- The promise, in their words. Who said what about the data, and when: “The CRM has been our source of truth since the migration.”
- How you found out and measured it. Within a day or two, profile the fields your outcome depends on: blanks, duplicates, join coverage, agreement with a hand-checked sample.
- What it breaks. Which metric can’t be reached, and which part of the plan still stands.
- The conversation. Who you told and what you showed them. Tell them once you have the measurement, not once you have the plan, and say when the options will follow. Numbers and examples, not adjectives, and no blame: whoever promised was probably describing the data they use daily.
- The revised plan. The options you offered, with the cost of each: narrow to the reliable slice, fix it at the source with their data owner, clean it in your pipeline and carry that forever, or move the date. Which they chose, and who owns the fix on their side.
- The result and the habit. What shipped, and what you now check in week one.
Say the finding as one sentence that puts your count next to the outcome it breaks, such as “The failure code is blank on most work orders, and it’s the field the model learns from”, with the count you measured in place of “most”.
The trap is quiet heroics: absorbing the cleanup yourself to protect the date. It feels like ownership, but it hides the problem until the date slips anyway, and the customer loses the chance to choose.
Follow-ups
What the interviewer may ask next, once your first answer is on the table.
- Who had told you the data was clean, and how did they take the news?
- What would you have done if the customer refused to move either the date or the scope?
- Could you have found this in the first week? What stopped you?
Where answers go wrong
- Quietly absorbs the cleanup, working longer to hit the date with the original scope, so the customer learns about their data only when the date slips.
- Delivers the news as blame or adjectives (“their data was a mess”) with no measurement and no options, which hands the customer a complaint instead of a decision.
Answer this in two minutes
Write the answer you would say out loud. The clock starts with your first word.
Illustrative answer about a fictional project
I was the deployed engineer at a logistics software company, building delivery time estimates for a building-materials distributor with six depots. What they’d bought was a text to each contractor with a two-hour arrival window, and the target was 80 percent of deliveries arriving inside it.