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

5.3 VALIDATING YOUR PARTITION

Because the legitimacy of the entire Data Science Methodology depends on the validity of the partition, it is important to check that the training data set and the test data set do not differ systematically from each other. We can do this by checking, on a variable‐by‐variable basis, whether the training and test sets differ. Because there may be many variables in the data set, we restrict ourselves to spot‐checking a small set of randomly chosen variables. Depending on the variable types involved, different statistical tests are required.

  • For a numerical variable, use the two‐sample t‐test for the difference in means.
  • For a categorical variable with two classes, use the two‐sample Z‐test for the difference in proportions.
  • For a categorical variable with more than two classes, use the test for the homogeneity of proportions.

For details on how to perform these tests, please see our earlier text.1