Book Image

Learning Predictive Analytics with R

By : Eric Mayor
Book Image

Learning Predictive Analytics with R

By: Eric Mayor

Overview of this book

This book is packed with easy-to-follow guidelines that explain the workings of the many key data mining tools of R, which are used to discover knowledge from your data. You will learn how to perform key predictive analytics tasks using R, such as train and test predictive models for classification and regression tasks, score new data sets and so on. All chapters will guide you in acquiring the skills in a practical way. Most chapters also include a theoretical introduction that will sharpen your understanding of the subject matter and invite you to go further. The book familiarizes you with the most common data mining tools of R, such as k-means, hierarchical regression, linear regression, association rules, principal component analysis, multilevel modeling, k-NN, Naïve Bayes, decision trees, and text mining. It also provides a description of visualization techniques using the basic visualization tools of R as well as lattice for visualizing patterns in data organized in groups. This book is invaluable for anyone fascinated by the data mining opportunities offered by GNU R and its packages.
Table of Contents (23 chapters)
Learning Predictive Analytics with R
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Exercises and Solutions
Index

Computing the performance of classification


There are several measures of performance that we can compute from the preceding table:

  • The true positive rate (or sensitivity) is computed as the number of true positives divided by the number of true positives plus the number of false negatives. In our example, sensitivity is the probability that a survivor is classified as such. Sensitivity in this case is:

    168 / (168 + 186) = 0.4745763

  • The true negative rate (or specificity) is computed as the number of true negatives divided by the number of true negatives plus the number of false positives. In our example, specificity is the probability that a nonsurvivor is classified as such. Specificity in this case is:

    645 / (645 + 60) = 0.9148936

  • The positive predictive value (or precision) is computed as the number of true positives divided by the number of true positives plus the number of false positives. In our example, precision is the probability that individuals classified as survivors are actually...