One of the challenges indexers face is to determine what size an index needs to be in order to best serve the reader. Occasionally there will be limitations on the space available for an index, that are usually related to the number of signatures needed during the production process, but for the most part, indexers are responsible for determining index length.
Like all good editing, indexing requires a careful balance of “what is left in” versus “what is left out.” We are all familiar with information overload. Too much irrelevant information can obscure the important stuff. Nonessential entries in an index can lead the reader on a wild goose chase through the text, which is both frustrating and time-consuming.
A good indexer will provide enough information to get the reader where they need to go in the text without cluttering up the index with entries that do not provide useful information.
Like all good things, indexing can be overdone. It important to determine the appropriate depth of indexing for a book. Some texts can be indexed lightly and serve the reader, whereas other texts require more in-depth indexing.
For example, a text that presents a series of case studies that all support the same research would include entries related to the research subject and the case studies would be indexes with enough information to the get the reader to where they need to go in the text. A book containing case studies about physical therapy would not delve too deeply into the specific details of the subject in the case studies.
For example, a case study might include this sentence: “Marsha, a middle school student in Oakridge, IL, complained of pain in her wrists while performing repetitive tasks.” Examples of appropriate main headings would be “adolescents,” “wrist pain,” and “repetitive takes.” Main headings related to “middle school” or “Illinois” would not be appropriate.
A skilled indexer will make the best determination for the length of an index, based on a thorough evaluation of the text with the consideration of its intended audience and will avoid bulking up an index with entries that are not related to the metatopic of a text.