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

11.6 MODEL EVALUATION FOR ESTIMATION

We can use the regression equation to make predictions (estimates) of sales per visit. For example, consider Customer 1 in the training set, who goes 333 days between purchases and who does not have a store credit card (Credit Card = 0). Plugging these values into the regression equation, we obtain:

equationSalesper^Visit=73.62+0.1637(333)+22.14(0)=$128.13--

That is, using the regression model, we would estimate the average sales per visit for this customer to be imagesy^=$128.13--actual sales per visit for this customer is y = $184.23. So, the prediction error (residual) for this customer is:

equationpredictionerror=(yy^)=184.23128.13=$56.10--

So, this customer spends $56.10 more than expected, given his or her days between visits and credit card status.

The typical size of the prediction error is given by the statistic s, the standard error of the estimate.

equations=MSE=SSEnp1=(yy^)2n−...