Book Image

Regression Analysis with R

By : Giuseppe Ciaburro
Book Image

Regression Analysis with R

By: Giuseppe Ciaburro

Overview of this book

Regression analysis is a statistical process which enables prediction of relationships between variables. The predictions are based on the casual effect of one variable upon another. Regression techniques for modeling and analyzing are employed on large set of data in order to reveal hidden relationship among the variables. This book will give you a rundown explaining what regression analysis is, explaining you the process from scratch. The first few chapters give an understanding of what the different types of learning are – supervised and unsupervised, how these learnings differ from each other. We then move to covering the supervised learning in details covering the various aspects of regression analysis. The outline of chapters are arranged in a way that gives a feel of all the steps covered in a data science process – loading the training dataset, handling missing values, EDA on the dataset, transformations and feature engineering, model building, assessing the model fitting and performance, and finally making predictions on unseen datasets. Each chapter starts with explaining the theoretical concepts and once the reader gets comfortable with the theory, we move to the practical examples to support the understanding. The practical examples are illustrated using R code including the different packages in R such as R Stats, Caret and so on. Each chapter is a mix of theory and practical examples. By the end of this book you will know all the concepts and pain-points related to regression analysis, and you will be able to implement your learning in your projects.
Table of Contents (15 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Regression trees


Decision trees are used to predict a response or class y from several input variables x1, x2,…,xn. If y is a continuous response, it's called a regression tree, if y is categorical, it's called a classification tree. That's why these methods are often called Classification and Regression Tree (CART). The algorithm is based on the following procedure: at each node of the tree, we check the value of one the input xi and depending of the (binary) answer we continue to the left or to the right branch. When we reach a leaf we will find the prediction.

This algorithm starts from grouped data into a single node (root node) and executes a comprehensive recursion of all possible subdivisions at every step. At each step, the best subdivision is chosen, that is, the one that produces as many homogeneous branches as possible.

In the regression trees, we try to partition the data space into small-enough parts where we can apply a simple different model on each part. The non leaf part of...