Measure Success for a New Chat System
Company: Roblox
Role: Data Scientist
Category: Analytics & Experimentation
Difficulty: medium
Interview Round: Technical Screen
# Measure Success for a New Chat System
A social platform is considering a new chat system. Design a measurement framework and an experiment to decide whether the launch is successful. Explain how you would choose a primary metric, guardrails, randomization unit, and launch criterion. The new system's specific changes are not supplied, so begin by clarifying the intended user benefit.
### What a Strong Answer Covers
- A user outcome that represents useful communication rather than raw message volume.
- Primary and guardrail definitions with stable units and observation windows.
- An experimental design that accounts for communication between treated and control users.
- A launch decision based on practical effects, uncertainty, reliability, and safety.
```hint Messages involve more than one user
A change seen by one participant may change the experience or behavior of another participant assigned to control.
```
### Follow-up Questions
- How could total messages increase while the chat experience worsens?
- What would you do if adoption rose but conversation reliability degraded?
Overview: Build a chat-system launch framework with meaningful communication metrics, reliability and safety guardrails, and experiments that address network effects.
Read the full Roblox Data Scientist interview experience this question came from