Implement linear regression from scratch

Last updated: February 6, 2026

Quick Overview

Write a clean implementation of logistic regression without using ML libraries.

Google
Machine Learning
Data Scientist
Google
February 6, 2026
Data Scientist
Onsite
Machine Learning
Hard

5

8

1,517 solved


Write a clean implementation of logistic regression without using ML libraries.

Google asks this during the Onsite to assess your depth in ML. They expect you to discuss the mathematical foundations, practical considerations, and common pitfalls when applying these techniques in production.

What the Interviewer Expects
  • Derive key equations and explain the optimization process in depth
  • Discuss state-of-the-art variations and recent research developments
  • Analyze computational complexity and scalability
  • Implement core components from scratch with clean code
  • Discuss production deployment challenges and solutions
  • Compare with cutting-edge alternatives and justify your recommendation
Key Topics to Cover
Regularization techniques (L1, L2, dropout)
Class imbalance handling
Feature importance and selection
Model interpretability and explainability
Bias-variance trade-off
Gradient descent and optimization
How to Approach This
  1. Understand the bias-variance trade-off. High training accuracy but low test accuracy signals overfitting.
  2. Choose evaluation metrics carefully based on the problem. Accuracy alone is often insufficient.
  3. Feature engineering is often more impactful than model selection.
  4. Know when to use tree-based models (tabular data) vs neural networks (unstructured data).
  5. Handle class imbalance with SMOTE, class weights, or appropriate loss functions.
Possible Follow-up Questions
  • How would you handle a highly imbalanced dataset?
  • What regularization technique would you use and why?
  • What are the computational costs of this approach at scale?
  • When would you prefer a simpler model over a complex one?
Sharpen Your Skills on Codemia

Practice similar problems with our interactive workspace, get AI feedback, and track your progress.

Explore ML Interview Prep
Sample Answer
Core Concept Explanation

Start with a clear, intuitive explanation of the concept. Use analogies when helpful. Then go deeper into the mathematical foundations: **Key Intuiti...

Practical Application

**When to use**: Describe the scenarios where this technique is most effective. What data characteristics favor it? **When NOT to use**: Common pitfa...


Submit Your Answer
Markdown supported

Related Questions