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

10.4 CLUSTER VALIDATION

Cluster solutions should be validated. Since no predictions were made using the training data set, we simply reapply the k‐means algorithm, this time to the white_wine_test data set, and compare the results obtained with the training set. Table 10.2 contains the resulting mean variable values, by cluster. As shown in Table 10.3, the difference in mean values (training minus test sets) is relatively small. Analysts wishing further validation may perform two‐sample t‐tests here.

TABLE 10.2 Mean variable value, by cluster, for the white_wine_test data sets

Variable Cluster 1 : 638 wines
“Sweet Wines”
Cluster 2 : 1122 wines
“Dry Wines”
Sugar _z  1.07 −0.61
Alcohol _z −0.80  0.46

The Python results in Figure 10.3 are used for this table. The cluster labels “Cluster 1” and “Cluster 2” were reversed, for ease of interpretation...