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Chapter 3 of Foundations

Beyond linear models soon

Trees, ensembles and support vector machines for the cases a straight line cannot handle; unsupervised learning for finding structure without labels; and how to interpret what a model has learned.

soon This chapter is planned and not yet written. The outline below is the current plan; it may change.

What it will cover

  • Decision trees and why they overfit; random forests and gradient boosting
  • Support vector machines and the kernel idea
  • Unsupervised learning: principal component analysis and k-means clustering
  • Model interpretation: permutation importance, partial dependence, SHAP-style explanations
  • Choosing between model families with cross-validation
  • Lab 3: a tabular modelling bake-off on the solubility and breast cancer data

Planned learning outcomes

  1. Train and tune tree ensembles and SVMs with scikit-learn, and say when each is appropriate.
  2. Use PCA and clustering to explore a dataset without labels and interpret the components.
  3. Explain a fitted model’s behaviour to a scientist using permutation importance and partial dependence.

In the meantime

Chapters 0, 1 and 2 are complete and are the prerequisites for this chapter.