Explain overfitting and how to prevent it
Company: Pinterest
Role: Machine Learning Engineer
Category: Machine Learning
Difficulty: hard
Interview Round: Technical Screen
You are asked rapid-fire ML fundamentals questions.
1. **What is overfitting?** Explain it in terms of training vs. validation performance and generalization.
2. **How can you prevent or mitigate overfitting?** List practical techniques and when you would use them.
3. **What is the difference between L1 and L2 regularization?** Compare their effect on model weights, feature selection, optimization behavior, and typical use cases.
Quick Answer: This question evaluates understanding of overfitting, the relationship between training and validation performance and generalization, and knowledge of regularization concepts including differences between L1 and L2 penalties.