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

12.1 THE NEED FOR DIMENSION REDUCTION

High dimensionality in data science refers to when there are a large number of predictors in the data set. For example, 100 predictors describe a 100‐dimensional space. So, why do we need dimension reduction in data science?

  1. Multicollinearity. Typically, large databases have many predictors. It is unlikely that all of these predictors are uncorrelated. Multicollinearity, which occurs when there is substantial correlation among the predictors, can lead to unstable regression models.
  2. Double‐Counting. Inclusion of predictors which are highly correlated tends to overemphasize a particular aspect of the model, that is, essentially double‐counting this aspect. For example, suppose we are trying to estimate the age of youngsters using math knowledge, height, and weight. Since height and weight are correlated, the model is essentially double‐counting the physical component of the youngster, as compared to the intellectual component...