What is variance in cost function context?
Updated May 15, 2026
Short answer
Variance measures how much model predictions change with data.
Deep explanation
High variance leads to overfitting and unstable cost across datasets.
Real-world example
Deep decision trees overfitting training data.
Common mistakes
- Ignoring validation loss.
Follow-up questions
- How to reduce variance?
- What is bias-variance tradeoff?