Week 2 Recap: The Week Trees Stopped Voting and Started Correcting Each Other

The One-Line Summary: Week 2 crossed the line from ensembles that average away variance to ensembles that attack bias one correction at a time — six posts covering out-of-bag error, Extra Trees, AdaBoost, Gradient Boosting, the learning-rate trap and a family cheat sheet, and the honest theme running through all of them is that boosting gives you a better ceiling in exchange for the ability to ruin the model by trying too hard. The Handoff Week 1 ended on a single quantity: tree-to-tree…