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

3.8 IDENTIFYING OUTLIERS

Once the numeric fields are standardized, one may use the z‐values to identify outliers, which are records with extreme values along a particular dimension or dimensions. For example, consider the field number_of_contacts, which represents the number of customer contacts made over the course of the marketing campaign. The mean number of contacts per customer is 2.6, with a standard deviation of 2.7 (allowing for rounding). So, we obtain the standardized field as follows:

equationnumber_of_contacts_z=number_of_contacts2.62.7--

A rough rule of thumb is that a data value is an outlier if its z‐value is either greater than 3, or less than −3. For instance, a customer who had been contacted 10 times (which seems like a lot) would have standardized value,

equationnumber_of_contacts_z=102.62.7=2.7--

Thus, 10 contacts, while a lot, is not identified as an outlier using this method, since 2.7 < 3.

The...