Learn/Course 05
Classical ML · weeks 7

Trees, forests & gradient boosting

A marketplace must catch rare fraud without blocking trustworthy sellers.

Opening production brief

A measurable problem, before a model.

Users

Operators, product owners, and people affected by the trees & boosting decision.

Data

impurity gain, bagging, feature subsampling, pseudo-residuals with version, owner, event time, and availability contracts.

Constraints

A marketplace must catch rare fraud without blocking trustworthy sellers. Every solution must state latency, cost, capacity, and fallback limits.

Success

Offline evidence plus a deployable resolution: Calibrated random-forest and XGBoost baselines with cost-sensitive thresholds.

CHAPTER 1

Frame and baseline

Turn the production problem into explicit data, metric, and baseline contracts.

  1. 01

    Trees as learned decision rules

    Use trees as learned decision rules to move the trees & boosting production brief toward a defensible release.

    65–90 min · checkpoint · deterministic lab
  2. 02

    Random forests and diversity

    Use random forests and diversity to move the trees & boosting production brief toward a defensible release.

    65–90 min · checkpoint · deterministic lab
CHAPTER 2

Build and stress

Formalize the machinery, test counterexamples, and expose system limits.

  1. 03

    Gradient boosting as error correction

    Use gradient boosting as error correction to move the trees & boosting production brief toward a defensible release.

    65–90 min · checkpoint · deterministic lab
  2. 04

    XGBoost: regularized boosting at scale

    Use xgboost: regularized boosting at scale to move the trees & boosting production brief toward a defensible release.

    65–90 min · checkpoint · deterministic lab
CHAPTER 3

Resolve and operate

Join model behavior to architecture, observability, rollout, and rollback.

  1. 05

    Calibrating and explaining ensembles

    Use calibrating and explaining ensembles to move the trees & boosting production brief toward a defensible release.

    65–90 min · checkpoint · deterministic lab
  2. HW

    Rare-fraud ensemble decision system

    Compare a tree, forest, gradient boosting, and XGBoost with temporal validation and operational thresholding.

    Rubric · staged hints · reference resolution
Prerequisite guidance

1 concepts make this faster.

Prerequisites are guidance, never hard gates.

C04Classical baselinesA justified baseline across regression, Naive Bayes, kNN, and SVM.
Ready to work the problem?

Trees as learned decision rules

Start lesson 01