Book Image

Statistical Application Development with R and Python - Second Edition

Book Image

Statistical Application Development with R and Python - Second Edition

Overview of this book

Statistical Analysis involves collecting and examining data to describe the nature of data that needs to be analyzed. It helps you explore the relation of data and build models to make better decisions. This book explores statistical concepts along with R and Python, which are well integrated from the word go. Almost every concept has an R code going with it which exemplifies the strength of R and applications. The R code and programs have been further strengthened with equivalent Python programs. Thus, you will first understand the data characteristics, descriptive statistics and the exploratory attitude, which will give you firm footing of data analysis. Statistical inference will complete the technical footing of statistical methods. Regression, linear, logistic modeling, and CART, builds the essential toolkit. This will help you complete complex problems in the real world. You will begin with a brief understanding of the nature of data and end with modern and advanced statistical models like CART. Every step is taken with DATA and R code, and further enhanced by Python. The data analysis journey begins with exploratory analysis, which is more than simple, descriptive, data summaries. You will then apply linear regression modeling, and end with logistic regression, CART, and spatial statistics. By the end of this book you will be able to apply your statistical learning in major domains at work or in your projects.
Table of Contents (19 chapters)
Statistical Application Development with R and Python - Second Edition
Credits
About the Author
Acknowledgment
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
Index

Model selection


The method of removal of covariates in the The multicollinearity problem section depended solely on the covariates themselves. However, it may happen more often that the covariates in the final model are selected with respect to the output. Computational cost is almost a non-issue these days and especially for not-so-large datasets! The question that arises then is, can one retain all possible covariates in the model, or do we have any choice of covariates that meet certain regression metrics, say R 2 > 60 percent?

The problem is that having more covariates increases the variance of the model, while having less of them will have a large bias. The philosophical Occam's Razor principle applies here too, and the best model is the simplest model. In our context, the smallest model that fits the data is the best. There are two types of model selection: stepwise procedures and criterion-based procedures. In this section, we will consider both the procedures.

Stepwise procedures...