In Praise of Indexes

SAS Press recently discontinued selling physical books, and now offers publications only in an electronic format (EPUB, Kindle, and PDF). I’m sure this is not an isolated incident and many other smaller publishing houses are going the same route.

I recently purchased the 3rd edition of Kirk Paul Lafler’s useful book, PROC SQL: Beyond the Basics Using SAS. I have the first and second editions of his book in softcover, and I was pleased to find that I could order a physical copy of his third edition through Amazon. After receiving the book, I quickly discovered that the third edition no longer includes an index!

I contacted SAS about the omission of the index, and received a prompt and courteous reply:

“You are correct about the index.  Indexes are no longer a standard part of our print books.  I do understand your concern, and have forwarded your feedback to the appropriate editors. All of our e-books are searchable. If you would like a complimentary copy of the corresponding e-book, I will be happy to forward that to you.”

I learned that neither the hardcopy nor the electronic version of the book contains an index.

I know I am 63 years old, and maybe not as immersed in modern technology as my younger colleagues, but since when did an index become a dispensable part of any non-fiction book?

First page of the index of PROC SQL: Beyond the Basics Using SAS, Second Edition

A good index is like a table of contents, only much more detailed. Sure, you can search a PDF for a particular term, but what if you can’t think of the term you’re searching for? For example, you might not remember that the type of many-to-many join you are looking for is called a Cartesian product, but when you see this term in the index it jogs your memory and you can find it on pages 237 and 242, which then leads you to the term cross join.

Another problem with searching through a document is that I have yet to see any search provide the ability to search for more than one non-contiguous terms at a time on a page or adjacent pages. A well-crafted index is often more effective than one-dimensional searching at finding topics that can’t easily be reduced to a single word or term.

Index subheadings, such as shown for CASE expressions above, are also hard to replace with one-dimensional searching.

Indexing is so important and requires such skill (to do it right) that there is even a professional organization for it: the American Society for Indexing.

I hope you can see now that every non-fiction book, printed or electronic, needs an index to help you quickly find the information you need.

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