Demo case file · Technical
E-commerce marketplace
Data Scientist
This is a demo case file: a realistic example written from commonly known interview formats, not a real candidate's interview experience.
Questions asked
- Checkout conversion dropped 8% week over week. How do you find out why?
- Write a SQL query that returns each user's first order date and how many orders they placed within 30 days of it.
- An A/B test of a new recommendations widget shows +2% revenue per user with p = 0.04, but it only ran for four days. Would you ship it?
What to expect
Half product sense, half hands-on. For the conversion drop they wanted me to rule out data and tracking problems, then segment by platform, country and traffic source before guessing at causes. On the A/B test they were looking for novelty effects, weekly seasonality, and checking the traffic split was actually 50/50.
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