Chapter 6. Statistical Machine Learning

Recent advances in statistics have been devoted to developing more powerful automated techniques for predictive modeling—both regression and classification. These methods fall under the umbrella of statistical machine learning, and are distinguished from classical statistical methods in that they are data-driven and do not seek to impose linear or other overall structure on the data. The K-Nearest Neighbors method, for example, is quite simple: classify a record in accordance with how similar records are classified. The most successful and widely used techniques are based on ensemble learning applied to decision trees. The basic idea of ensemble learning is to use many models to form a prediction as opposed to just a single model. Decision trees are a flexible and automatic technique to learn rules about the relationships between predictor variables and outcome variables. It turns out that the combination of ensemble learning with decision trees leads to the top-performing off-the-shelf predictive modeling techniques.

The development of many of the techniques in statistical machine learning can be traced back to the statisticians Leo Breiman (see Figure 6-1) at the University of California at Berkeley and Jerry Friedman at Stanford University. Their work, along with other researchers at Berkeley and Stanford, started with the development of tree models in 1984. The subsequent development of ensemble methods of bagging and boosting in the ...

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