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

Polynomial regression


Polynomial models can be used in situations where the relationship between response and explanatory variables is curvilinear. Sometimes, a nonlinear relationship in a small range of explanatory variables can also be modeled by polynomials.

A polynomial quadratic (squared) or cubic (cubed) term turns a linear regression model into a polynomial curve. However, since it is the explanatory variable that is squared or cubed and not the Beta coefficient, it still qualifies as a linear model. This makes it a nice, straightforward way to model curves, without having to model complicated nonlinear models.

In polynomial regression, some predictors appear in degrees equal to or greater than two. The model continues to be linear in its parameters. For example, a second-degree parabolic regression model looks like this:

This model can easily be estimated by introducing a second-degree term in the regression model. The difference is that in polynomial regression, the equation produces...