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Explain ML statistics and model design concepts

Last updated: Mar 29, 2026

Quick Overview

This question evaluates mastery of probability and statistics, machine-learning foundations, deep-learning architectures, causal inference, and end-to-end model design concepts within the ML System Design domain.

  • hard
  • Amazon
  • ML System Design
  • Machine Learning Engineer

Explain ML statistics and model design concepts

Company: Amazon

Role: Machine Learning Engineer

Category: ML System Design

Difficulty: hard

Interview Round: Technical Screen

##### Question What is a moment generating function and how is it used? Compare exponential and Poisson distributions. Explain statistical distance and statistical difference. Describe the steps of a hypothesis test. State and explain the Law of Large Numbers. What common assumptions underlie machine-learning models? How does multicollinearity affect Random Forests versus XGBoost? How does number of trees impact performance? Define overfitting and methods to prevent it. Name deep-learning models you are familiar with. Compare RNN and LSTM; explain RNN drawbacks and LSTM structure. What is an autoencoder and its use cases? How does the attention mechanism work? Describe the architecture of a CNN. Explain basic principles of causal inference. Design an ML system to identify relevant users.

Quick Answer: This question evaluates mastery of probability and statistics, machine-learning foundations, deep-learning architectures, causal inference, and end-to-end model design concepts within the ML System Design domain.

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Amazon logo
Amazon
Jul 29, 2025, 8:05 AM
Machine Learning Engineer
Technical Screen
ML System Design
6
0

Technical Phone Screen: Theory + System Design

Probability and Statistics

  1. Define a moment generating function (MGF) and explain how it is used.
  2. Compare the exponential and Poisson distributions and explain how they relate.
  3. Explain "statistical distance" vs. "statistical difference" (significance). Provide examples.
  4. Describe the steps of a hypothesis test.
  5. State and explain the Law of Large Numbers.

Machine Learning Foundations

  1. What common assumptions underlie machine-learning models?
  2. How does multicollinearity affect Random Forests versus XGBoost?
  3. How does the number of trees impact performance (Random Forest vs. Gradient Boosting/XGBoost)?
  4. Define overfitting and methods to prevent it.

Deep Learning Concepts

  1. Name deep-learning model families you are familiar with.
  2. Compare RNN and LSTM; explain RNN drawbacks and LSTM structure.
  3. What is an autoencoder and what are typical use cases?
  4. How does the attention mechanism work?
  5. Describe the architecture of a CNN.

Causal Inference

  1. Explain the basic principles of causal inference and common methods.

System Design

  1. Design an ML system to identify relevant users (e.g., for targeting a new feature or campaign). Outline problem framing, data, model, serving, and evaluation.

Solution

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