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LinkedIn·Machine Learning Engineer·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

LinkedIn ML Engineer screen, pretty heavy on ML fundamentals. One question but they really wanted you to go deep on it, not just recite a definition.

Questions Asked (1)

Q1

Why is logistic regression a good fit for binary classification, and how can you justify treating its output as a probability?

Technical Trade-offsAlgorithms & Data Structures
Author's notes

This sounds like a warmup question until they ask you to actually derive things.

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AI HintsAI Generated

Suggested Approach

Start by explaining why logistic regression is naturally suited for binary classification, focusing on its probabilistic output and decision boundary. Then justify the probabilistic interpretation by linking the logistic function to the log-odds and maximum likelihood estimation. Conclude by discussing practical implications and trade-offs.

Pro tip: Mention that logistic regression outputs well-calibrated probabilities by default, but you can further improve calibration with techniques like Platt scaling if needed—this shows awareness of real-world deployment concerns.

1. Define the problem

State that binary classification requires predicting a probability between 0 and 1, and logistic regression directly models this.

2. Explain the logistic function

Describe how the logistic (sigmoid) function maps any real-valued linear combination to (0,1), ensuring valid probability outputs.

3. Justify probability interpretation

Connect the output to the log-odds: log(p/(1-p)) = w·x + b, and explain that maximum likelihood estimation yields probabilities that reflect true class frequencies.

4. Discuss decision boundary and threshold

Mention that a threshold (e.g., 0.5) converts probabilities to class labels, and that the threshold can be tuned based on business needs.

5. Address assumptions and trade-offs

Note that logistic regression assumes linearity in log-odds, which may be limiting, but its interpretability and probabilistic nature are advantages.

Key Points to Mention

  • Sigmoid function maps real values to (0,1)
  • Log-odds (logit) link function: log(p/(1-p)) = w·x + b
  • Maximum likelihood estimation for parameter learning
  • Probabilistic output allows for calibrated confidence and threshold tuning
  • Decision boundary is linear in feature space
  • Assumption of linear relationship between features and log-odds

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.