Why Your Book Needs an Index (Extract from the ASI Special Interest Group http://www.historyindexers.org/why-your-book-needs-an-index/ Original 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 subjectivity of a reader, or the objectivity of a professional indexer. The role of the indexer is to match the author’s content with the reader’s specific information needs. The indexer can imagine potential readers and anticipate their needs when indexing the book.
An index is successful only if it is approachable and usable. Usable indexes improve the written work and build reader confidence in the author. The purpose of the index is to save the reader time and frustration 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, they may be able to index their work in a useful way.
Finally, keep in mind the index can't 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 or two.
A well thought out index will use cross-references and alternate search terms that can lead human readers to content information, which 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 search does not have that capacity. Artificial Intelligence algorithms are not sentient, do not understand human context, and as expert Gary Marcus writes, are "unable to construct internal models of how the world works."
Cross-references must be anticipated. For example, will a reader expect to find the generic term Native American, or Indigenous Peoples, or a specific band name? The Elements of Indigenous Style by Gregory Younging provides a paradigm shift in thinking.
In back-of-the-book indexing, specific formatting principles are followed. Publishers may specify whether the index should be indented or run-in style as well as other style guidelines reflective of the book content. Indexing software accomodates these specifications. If an author is planning on preparing their own index, utilization of formatting software can be a costly investment.
Authors invest many hours researching and rewriting to prepare a book they are proud of and willing to share with readers. The index is a reflection of that dedication and care.