Book Image

Data Analysis Using SQL and Excel - Second Edition

By : Gordon S. S. Linoff
Book Image

Data Analysis Using SQL and Excel - Second Edition

By: Gordon S. S. Linoff

Overview of this book

Data Analysis Using SQL and Excel, 2nd Edition shows you how to leverage the two most popular tools for data query and analysis—SQL and Excel—to perform sophisticated data analysis without the need for complex and expensive data mining tools. Written by a leading expert on business data mining, this book shows you how to extract useful business information from relational databases. You'll learn the fundamental techniques before moving into the "where" and "why" of each analysis, and then learn how to design and perform these analyses using SQL and Excel. Examples include SQL and Excel code, and the appendix shows how non-standard constructs are implemented in other major databases, including Oracle and IBM DB2/UDB. The companion website includes datasets and Excel spreadsheets, and the book provides hints, warnings, and technical asides to help you every step of the way. Data Analysis Using SQL and Excel, 2nd Edition shows you how to perform a wide range of sophisticated analyses using these simple tools, sparing you the significant expense of proprietary data mining tools like SAS.
Table of Contents (18 chapters)
Free Chapter
1
Foreword
17
EULA

What Months and Payment Types Have Unusual Affinities for Which Types of Products?

This question is similar to the question in the previous section, except that it uses three columns instead of two columns. Answering this question introduces the multidimensional chi-square calculation. This is very similar to the two-dimensional version, the only differences being some adjustments to the formulas.

Multidimensional Chi-Square

Adding additional dimensions does not change how the chi-square value is calculated. It is still the sum of the squares of the differences between a count and the expected count divided by the expected count.

What changes is the formula for the expected value. For two-dimensions, this is the product of the counts along each of two dimensions divided by the total count. This formula generalizes to more dimensions. For three, it is the product of the counts along each of the three dimensions divided by the total count squared. Notice the “squared” in...