Evaluate impact of short videos in feed
Company: Meta
Role: Data Engineer
Category: System Design
Difficulty: hard
Interview Round: Onsite
## Scenario
You work on a social app’s main **News Feed**. The team wants to introduce a **short-form video module ("Reels")** into the feed.
## Prompt
1. How would you determine whether adding Reels to the News Feed is **successful**?
2. What **metrics** would you define (primary + secondary/guardrails)?
3. How would you design an **experiment / launch plan** to measure impact?
## Notes / Assumptions
- The feed currently contains mixed content (text, images, long videos, links).
- Reels may affect both **consumption** (viewing) and **distribution** (other content getting less exposure).
- You have standard event logging for impressions, clicks, watch time, likes, comments, shares, hides, follows, etc.
Overview: This question evaluates competency in metrics definition, causal experimentation, product analytics, and feed system behavior within the System Design and Data Engineering domain.
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