Define hand-waving accuracy and launch decision
Company: Meta
Role: Data Scientist
Category: Analytics & Experimentation
Difficulty: easy
Interview Round: Onsite
## Context
You work on a VR product that introduces a new interaction feature called **hand waving** (the system detects when a user is waving their hand and triggers some UI/interaction). Engineering believes it’s ready to launch, but you (as the Data Scientist) are asked to evaluate readiness.
## Task
1. **Define “hand-waving accuracy.”**
- What exactly is the unit of evaluation (frame, time window, gesture event, session)?
- What labels/ground truth are needed and how would you obtain them?
- Which error types matter most (false positives vs false negatives) and why?
- What metrics would you report (e.g., precision/recall/F1, latency, stability), and how would you choose thresholds?
2. **Connect model/metric quality to product outcomes.**
- Propose a set of **primary**, **diagnostic**, and **guardrail** metrics that tie detection quality to user experience (e.g., engagement, retention, frustration, safety).
- Describe potential confounders (novelty effects, device differences, power users vs new users) and how you would handle them.
3. **Data collection and aggregation.**
- What events/logs would you instrument?
- How would you aggregate the metrics (per event, per user/day, per session) and why?
4. **Diagnostics & visualization.**
- Name at least 2 diagnostic cuts (e.g., lighting, device type, hand-tracking quality, motion intensity) and the plots you’d use to identify failure modes.
5. **Launch recommendation & exec reporting.**
- What would you present to a VP-level audience as the single most important KPI (plus 2–3 supporting metrics)?
- What is your launch decision framework (ship, ship-to-% ramp, delay), and what are the go/no-go criteria?
Quick Answer: This question evaluates a data scientist's ability to define and operationalize detection metrics, design instrumentation and diagnostics, connect model-level quality to product KPIs, and make a data-driven launch decision for a hand-waving interaction feature within the Analytics & Experimentation domain.