Debug a model with class imbalance
Last updated: August 13, 2025
Quick Overview
Your model shows poor recall. Walk through your debugging process and potential fixes.
Zillow
August 13, 202581
6
1,674 solved
Your model shows poor recall. Walk through your debugging process and potential fixes.
Machine learning questions at Zillow test both theoretical understanding and practical experience. This Phone Screen question evaluates your knowledge of ML fundamentals and your ability to apply them to real-world problems.
What the Interviewer Expects
- Explain the mathematical foundations with clarity
- Discuss practical implementation considerations and hyperparameter tuning
- Analyze the technique's strengths and weaknesses for different data types
- Demonstrate understanding of evaluation methodology and metrics
- Connect theory to real-world applications with concrete examples
Key Topics to Cover
How to Approach This
- Understand the bias-variance trade-off. High training accuracy but low test accuracy signals overfitting.
- Choose evaluation metrics carefully based on the problem. Accuracy alone is often insufficient.
- Feature engineering is often more impactful than model selection.
- Know when to use tree-based models (tabular data) vs neural networks (unstructured data).
- 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?
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Explore ML Interview PrepSample Answer
Core Concept: Class Imbalance and Recall
Class imbalance occurs when classes in a dataset are not represented equally. In the context of Zillow, this may manifest as a model predicting home prices or features where fewer instances represent ...
How it Works: Mathematical Mechanisms
To address class imbalance, one common approach is to utilize techniques such as re-sampling. This can include oversampling the minority class (e.g., generating synthetic examples using SMOTE) or unde...
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