Measure impact of bot mitigation via experiment

Quick Overview

This question evaluates experiment design and causal inference skills for platform analytics, covering interference management, metric and guardrail definition, power and duration calculations, eligibility and exclusions, novelty/adaptation considerations, and diagnostics for bot‑mitigation interventions.

Measure impact of bot mitigation via experiment

Company: Meta

Role: Data Scientist

Category: Analytics & Experimentation

Difficulty: hard

Interview Round: Onsite

You will measure the impact of deploying a bot-mitigation system that hides or rate-limits suspected bots’ comments. Design an experiment covering: 1) Randomization unit and interference: justify account-level vs cluster (graph/community) randomization to limit spillovers; propose a stepped-wedge ramp. 2) Primary success metrics: human-visible comments per human DAU, human creator retention, report rates; define guardrails (new-user activation, moderation backlog, latency). 3) Eligibility and exclusions: how to handle already-flagged accounts and high-risk geos; pre-exposure period and CUPED to reduce variance. 4) Power: assuming baseline human-visible comments/DAU = 5.5 and MDE = −2% total comments but +1% human-visible comments, outline sample-size and duration calculations for a 14-day test with day-level clustering. 5) Novelty and adaptation: plan for novelty decay, contamination from bot migration, and adversarial learning. 6) Fallback when A/B is infeasible: difference-in-differences with synthetic controls and high-frequency pre-trends checks. 7) Diagnostics if FP rises: define on-experiment holdouts and stratified analysis (new vs veteran users, creators vs consumers). Deliver an analysis plan and stop/go criteria.

Overview: This question evaluates experiment design and causal inference skills for platform analytics, covering interference management, metric and guardrail definition, power and duration calculations, eligibility and exclusions, novelty/adaptation considerations, and diagnostics for bot‑mitigation interventions.

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Oct 13, 2025
hardData ScientistOnsiteAnalytics & Experimentation
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Experiment Design: Measuring the Impact of a Bot‑Mitigation System

Context

You are evaluating a production change to a large social platform that hides or rate‑limits comments from suspected bot accounts. The goal is to improve the human experience without harming creators or platform health. You must design an experiment (and fallback causal strategy) that addresses interference, metrics, eligibility, power, novelty/adaptation, and diagnostics.

Tasks

  1. Randomization unit and interference
  • Choose and justify the randomization unit (account‑level vs. graph/community clusters) to limit spillovers.
  • Describe how you'll handle interference via the social graph (viewers, commenters, creators).
  • Propose a stepped‑wedge ramp plan.
  1. Primary success metrics and guardrails
  • Primary: human‑visible comments per human DAU, human creator retention, report rates.
  • Define guardrails: new‑user activation, moderation backlog, latency, etc.
  1. Eligibility and exclusions
  • Define which users/geos are eligible.
  • Specify how to handle already‑flagged accounts and high‑risk geos.
  • Include a pre‑exposure period and use CUPED to reduce variance.
  1. Power and duration
  • Baseline: human‑visible comments/DAU = 5.5.
  • MDEs: −2% total comments; +1% human‑visible comments.
  • Outline sample‑size and duration calculations for a 14‑day test with day‑level clustering.
  1. Novelty and adaptation
  • Plan for novelty decay, contamination from bot migration, and adversarial learning.
  1. Fallback when A/B is infeasible
  • Use difference‑in‑differences with synthetic controls and high‑frequency pre‑trends checks.
  1. Diagnostics if false positives rise
  • Define on‑experiment holdouts and stratified analysis (new vs. veteran users, creators vs. consumers).

Deliver an analysis plan with stop/go criteria.

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