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Design robber detection from surveillance video

Last updated: Apr 7, 2026

Quick Overview

This question evaluates applied machine learning and computer vision system-design skills, including precise task definition, data and labeling strategy for rare events, temporal modeling, deployment constraints, and ethical risk assessment.

  • easy
  • Capital One
  • Machine Learning
  • Data Scientist

Design robber detection from surveillance video

Company: Capital One

Role: Data Scientist

Category: Machine Learning

Difficulty: easy

Interview Round: Technical Screen

You’re a Data Scientist on a team building a computer-vision system for public-safety monitoring. ## Problem Design an ML system that uses fixed surveillance cameras to **detect potential robbers in real time** and trigger an alert to a human operator. ## What to cover 1. **Define the task precisely** - What is the model predicting (e.g., “robbery in progress”, “person-of-interest”, “weapon present”, “suspicious behavior”)? - What is the unit of prediction (frame, clip, track, event) and decision thresholding? 2. **Data & labeling strategy** - Data sources (historical footage, staged data, public datasets) and how you will label positives/negatives. - How you’ll handle **rare events**, noisy labels, and ambiguous cases. 3. **Modeling approach** - Candidate pipelines (detection + tracking + action recognition, multimodal, temporal models, etc.). - How you will deal with occlusion, lighting, camera angle differences, and domain shift. 4. **Evaluation plan** - Choose **primary metric(s)** and explain tradeoffs (e.g., precision/recall, false alarm rate per hour, detection latency). - Offline evaluation vs online evaluation; how you’d estimate performance under class imbalance. 5. **Deployment & monitoring** - Latency/throughput constraints, edge vs cloud inference, model updates. - Monitoring for drift and performance regression. 6. **Risk, fairness, and privacy** - Potential harms (misidentification, demographic bias, privacy violations). - Mitigations, governance, and human-in-the-loop design. Assume you can ask clarifying questions about operational constraints (camera FPS, compute budget, allowable false alarm rate, legal/privacy requirements).

Quick Answer: This question evaluates applied machine learning and computer vision system-design skills, including precise task definition, data and labeling strategy for rare events, temporal modeling, deployment constraints, and ethical risk assessment.

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Capital One
Feb 22, 2026, 8:50 AM
Data Scientist
Technical Screen
Machine Learning
62
0
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You’re a Data Scientist on a team building a computer-vision system for public-safety monitoring.

Problem

Design an ML system that uses fixed surveillance cameras to detect potential robbers in real time and trigger an alert to a human operator.

What to cover

  1. Define the task precisely
    • What is the model predicting (e.g., “robbery in progress”, “person-of-interest”, “weapon present”, “suspicious behavior”)?
    • What is the unit of prediction (frame, clip, track, event) and decision thresholding?
  2. Data & labeling strategy
    • Data sources (historical footage, staged data, public datasets) and how you will label positives/negatives.
    • How you’ll handle rare events , noisy labels, and ambiguous cases.
  3. Modeling approach
    • Candidate pipelines (detection + tracking + action recognition, multimodal, temporal models, etc.).
    • How you will deal with occlusion, lighting, camera angle differences, and domain shift.
  4. Evaluation plan
    • Choose primary metric(s) and explain tradeoffs (e.g., precision/recall, false alarm rate per hour, detection latency).
    • Offline evaluation vs online evaluation; how you’d estimate performance under class imbalance.
  5. Deployment & monitoring
    • Latency/throughput constraints, edge vs cloud inference, model updates.
    • Monitoring for drift and performance regression.
  6. Risk, fairness, and privacy
    • Potential harms (misidentification, demographic bias, privacy violations).
    • Mitigations, governance, and human-in-the-loop design.

Assume you can ask clarifying questions about operational constraints (camera FPS, compute budget, allowable false alarm rate, legal/privacy requirements).

Solution

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