One Door Each

A medium Data Modeling interview practice problem on DataDriven. Write and execute real data modeling code with instant feedback.

Domain

Data Modeling

Difficulty

medium

Seniority

L5

Problem

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 joining each user's variant assignment onto our existing event log, which stays untouched, and counting only the events that occurred after the moment that user was enrolled. Design the data model so a user can never land in two variants of the same experiment, and so an analyst rolling metrics up by variant can tell the control apart from the treatment groups.

Summary

Every user picks a lane and stays in it. Model the world so the numbers stay honest.

Practice This Problem

Solve this Data Modeling problem with real code execution. DataDriven runs your solution and checks it automatically.