Why Your Book Needs an Index (Extract from the ASI Special Interest Group http://www.historyindexers.org/why-your-book-needs-an-index/ Article by Mindy Reed)
While it may seem that the author of a book would be best at preparing the index, since he or she knows the work most intimately, too often they lack the objectivity of the reader. The role of the indexer is to match the author’s content with the reader’s specific information needs. The indexer visualizes potential readers and anticipates their needs when indexing the book.
An index is successful only if it is usable. Usable indexes improve the written work and builds reader confidence in the author. The purpose of the index is to save the reader time and energy in their search for relevant information. Rapid information retrieval is critical to the success of a book, manual, database or website.
That is not to say the author can never be the indexer. If the author can view their book from the perspective of the reader and understands how to use cross references to guide the reader through their work, then they may be able to index. Utilization of formatting software is a definite benefit to ensure meeting all the style requirements. However, it can be a costly investment if the author is planning on preparing only one index.
Remember, the index cannot be prepared until the book is in final layout from the publisher or printer. It requires final pagination to be prepared correctly. An index without correct page locators is worthless. Most publishers will require the index be prepared on a short lead-time, often no more than a week.
An index is not a concordance. A well thought out index will use cross-references and alternate terms to lead readers and users to information. That is why human intervention is still needed for index preparation. While a human person can distinguish between a singer (bass) and a fish (bass), an embedded word finder does not have that capacity.
Specific formatting principles must be followed. The publisher will provide the requirements in their style sheet. This will include if the index should be indented or run-in style, how it should be alphabetized (word by word or letter by letter, the locator range, punctuation and capitalization of headings).
Cross-references must be anticipated. For example, will a reader expect the generic term Native American, or aboriginal, or a specific band name?
Utilization of formatting software is a definite benefit to ensure meeting all the style requirements. However, it can be a costly investment if the author is planning on preparing only one index.
A Last Note:
Authors invest a lot of time in researching and rewriting to prepare a book they are proud of and willing to share with readers. The index should be a reflection of that dedication and care.