Book Image

Data Science Using Python and R

By : Chantal D. Larose, Daniel T. Larose
Book Image

Data Science Using Python and R

By: Chantal D. Larose, Daniel T. Larose

Overview of this book

Data science is hot. Bloomberg named a data scientist as the ‘hottest job in America’. Python and R are the top two open-source data science tools using which you can produce hands-on solutions to real-world business problems, using state-of-the-art techniques. Each chapter in the book presents step-by-step instructions and walkthroughs for solving data science problems using Python and R. You’ll learn how to prepare data, perform exploratory data analysis, and prepare to model the data. As you progress, you’ll explore what are decision trees and how to use them. You’ll also learn about model evaluation, misclassification costs, naïve Bayes classification, and neural networks. The later chapters provide comprehensive information about clustering, regression modeling, dimension reduction, and association rules mining. The book also throws light on exciting new topics, such as random forests and general linear models. The book emphasizes data-driven error costs to enhance profitability, which avoids the common pitfalls that may cost a company millions of dollars. By the end of this book, you’ll have enough knowledge and confidence to start providing solutions to data science problems using R and Python.
Table of Contents (20 chapters)
Free Chapter
1
ABOUT THE AUTHORS
17
INDEX
18
END USER LICENSE AGREEMENT

7.2 CLASSIFICATION EVALUATION MEASURES

We will develop classification evaluation measures for the case where we have a binary target variable. In order to apply the measures we will learn in this chapter, we will need to denote (arbitrarily, if desired) one of the two target outcomes as positive and one as negative. For example, suppose we are trying to predict income, a binary variable with values high income and low income. We could denote high income as positive and low income as negative.1

Now, the classification model evaluation measures we will learn in this chapter are functions of the entries in the contingency table2 generated by the classification model, the general form of which is shown in Table 7.1. Note that, by convention, the actual values are represented by the rows, while the predicted values are represented by the columns. The upper‐left cell in Table 7.1 represents the number of records where the model predicted a negative response and the actual response value...