Book Image

Hands-On Ensemble Learning with R

By : Prabhanjan Narayanachar Tattar
Book Image

Hands-On Ensemble Learning with R

By: Prabhanjan Narayanachar Tattar

Overview of this book

Ensemble techniques are used for combining two or more similar or dissimilar machine learning algorithms to create a stronger model. Such a model delivers superior prediction power and can give your datasets a boost in accuracy. Hands-On Ensemble Learning with R begins with the important statistical resampling methods. You will then walk through the central trilogy of ensemble techniques – bagging, random forest, and boosting – then you'll learn how they can be used to provide greater accuracy on large datasets using popular R packages. You will learn how to combine model predictions using different machine learning algorithms to build ensemble models. In addition to this, you will explore how to improve the performance of your ensemble models. By the end of this book, you will have learned how machine learning algorithms can be combined to reduce common problems and build simple efficient ensemble models with the help of real-world examples.
Table of Contents (17 chapters)
Hands-On Ensemble Learning with R
Contributors
Preface
12
What's Next?
Index

Why does ensembling work?


When using the bagging method, we combine the result of many decision trees and produce a single output/prediction by taking a majority count. Under a different sampling mechanism, the results had been combined to produce a single prediction for the random forests. Under a sequential error reduction method for decision trees, the boosting method also provides improved answers. Although we are dealing with uncertain data, which involves probabilities, we don't intend to have methodologies that give results out of a black box and behave without consistent solutions. A theory should explain the working and we need an assurance that the results will be consistent and there is no black magic about it. Arbitrary and uncertain answers are completely unwanted. In this section, we will look at how and why the ensembling solutions work, as well as scenarios where they will not work.

Ensembling methods have strong mathematical and statistical underpinnings that explain why...