Split Decision
A medium Data Modeling mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- Data Modeling
- Difficulty
- medium
- Seniority
- L5
Interview Prompt
We run dozens of product experiments at once on our consumer app, and each user who enters an experiment is locked to a single variant for its duration: either the control or one of the treatment groups. Analysts measure lift by comparing what users in each variant did after they were enrolled, joining their assignments back to our existing event log. Design the data model so a user can never land in two variants of the same experiment and so only post-enrollment behavior counts toward a variant's metrics.
Summary
One user, one experiment, one variant. No exceptions.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your data modeling solution with real code execution
- Get instant feedback and a hire/no-hire decision