Simulate and Compare Multi-Armed Bandit Strategies

Read the full interview experience this question came from →

Quick Overview

Compare epsilon-greedy, UCB1, and Thompson sampling in a reproducible Bernoulli bandit simulation with reward, pseudo-regret, and repeated-run uncertainty.

Simulate and Compare Multi-Armed Bandit Strategies

Company: Wayfair

Role: Applied Scientist

Category: Machine Learning

Difficulty: medium

Interview Round: Onsite

Build a small simulation that compares common multi-armed bandit strategies. Explain each strategy, record reward and regret, and use the experiment to discuss exploration versus exploitation. ### Constraints & Assumptions The source reports a bandit simulation exercise with AI and search tools allowed, but gives no arm distributions, horizon, or required output. For this practice discussion, use stationary independent Bernoulli arms with known probabilities available only to the simulator. Compare epsilon-greedy, UCB1, and Thompson sampling over repeated random seeds. This is an experimental simulation exercise rather than a fixed-output console task. ### Clarifying Questions Are rewards binary or continuous? Is the environment stationary? What is the horizon? Does the policy observe only the chosen arm's reward? How should reproducibility and uncertainty be reported? ### What a Strong Answer Covers Separate policy knowledge from simulator knowledge, implement each update correctly, distinguish realized reward from expected pseudo-regret, and compare repeated runs rather than a single lucky trajectory. Explain any generated code before relying on it. ### Follow-up Questions How do the results change with a small reward gap, a short horizon, nonstationary rewards, or a poorly chosen exploration rate? Why is sharing a seed alone insufficient to guarantee identical random consumption across policies?

Overview: Compare epsilon-greedy, UCB1, and Thompson sampling in a reproducible Bernoulli bandit simulation with reward, pseudo-regret, and repeated-run uncertainty.

Read the full Wayfair Applied Scientist interview experience this question came from

|Home/Machine Learning/Wayfair
Wayfair logo
Wayfair
Sep 10, 2026
mediumApplied ScientistOnsiteMachine Learning
0
0

Build a small simulation that compares common multi-armed bandit strategies. Explain each strategy, record reward and regret, and use the experiment to discuss exploration versus exploitation.

Constraints & Assumptions

The source reports a bandit simulation exercise with AI and search tools allowed, but gives no arm distributions, horizon, or required output. For this practice discussion, use stationary independent Bernoulli arms with known probabilities available only to the simulator. Compare epsilon-greedy, UCB1, and Thompson sampling over repeated random seeds. This is an experimental simulation exercise rather than a fixed-output console task.

Clarifying Questions Guidance

Are rewards binary or continuous? Is the environment stationary? What is the horizon? Does the policy observe only the chosen arm's reward? How should reproducibility and uncertainty be reported?

What a Strong Answer Covers Guidance

Separate policy knowledge from simulator knowledge, implement each update correctly, distinguish realized reward from expected pseudo-regret, and compare repeated runs rather than a single lucky trajectory. Explain any generated code before relying on it.

Follow-up Questions Guidance

How do the results change with a small reward gap, a short horizon, nonstationary rewards, or a poorly chosen exploration rate? Why is sharing a seed alone insufficient to guarantee identical random consumption across policies?

Loading comments...