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

Time to Next Event

The final topic in this chapter combines the ideas from survival analysis with repeated events. This topic is quite deep, and this section is just an introduction. The question is: How long until a customer places another order?

Idea behind the Calculation

To apply survival analysis to repeated events, each order needs the date of the next order in the household (if any). The order date and next order date provide the basic information needed for time-to-event survival analysis. The definitions for survival analysis are inverted from the last two chapters:

  • The “start” event is when a customer makes a purchase.
  • The “end” event is either the next purchase date or the cutoff date.

This terminology for repeated events is backward. “Survival” ends up meaning the survival of the customer’s “non-purchase” state. In fact, we are interested in the exact opposite of survival, 100%-Survival, which is the cumulative...