Book Image

Machine Learning with R Cookbook, Second Edition - Second Edition

By : Yu-Wei, Chiu (David Chiu)
Book Image

Machine Learning with R Cookbook, Second Edition - Second Edition

By: Yu-Wei, Chiu (David Chiu)

Overview of this book

Big data has become a popular buzzword across many industries. An increasing number of people have been exposed to the term and are looking at how to leverage big data in their own businesses, to improve sales and profitability. However, collecting, aggregating, and visualizing data is just one part of the equation. Being able to extract useful information from data is another task, and a much more challenging one. Machine Learning with R Cookbook, Second Edition uses a practical approach to teach you how to perform machine learning with R. Each chapter is divided into several simple recipes. Through the step-by-step instructions provided in each recipe, you will be able to construct a predictive model by using a variety of machine learning packages. In this book, you will first learn to set up the R environment and use simple R commands to explore data. The next topic covers how to perform statistical analysis with machine learning analysis and assess created models, covered in detail later on in the book. You'll also learn how to integrate R and Hadoop to create a big data analysis platform. The detailed illustrations provide all the information required to start applying machine learning to individual projects. With Machine Learning with R Cookbook, machine learning has never been easier.
Table of Contents (21 chapters)
Title Page
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Using the log-rank test


The log-rank test is used to find the difference between two curves. It is a nonparametric test. It is also known as the Mantel-Cox test. It compares the estimates of hazard functions at each observed time. It will test two hypotheses: there is no difference in the survival function based on gender, and there is a difference in survival function based on gender.

Getting ready

You need to have performed the previous recipes.

How to do it...

Perform the following step:

> survdiff(Surv(cancer$time, cancer$status)~cancer$sex)
 Output
    Call:
    survdiff(formula = Surv(cancer$time, cancer$status) ~ cancer$sex)
    N Observed Expected (O-E)^2/E (O-E)^2/V
    cancer$sex=1 138 112 91.5817 4.55228 10.3267
    cancer$sex=2 90 53 73.4183 5.67850 10.3267
    Chisq= 10.3 on 1 degrees of freedom, p= 0.00131116 

How it works...

The survdiff function displays the number of observations in a group; in our case, 138 males and 90 females. The observation shows the number of events that...