From the ASI website: Is the index to your book good enough for your readers? Here are some helpful insights for ensuring an excellent index.
Are the indexed terms appropriate for the intended audience? For example: “heart attack” in a book for the general public, “myocardial infarction” in a book for health professions; “Taxus” in a work for botanists or horticulturists, “Yew” in a work for home gardeners.
Are the main headings relevant to the needs of the reader? Are they pertinent, specific, comprehensive? Not too general yet not too narrow? Not inane or improbable.
Do main headings have not more than five to seven locators (page references)? If more, they should be broken down into subheadings.
Have see and see also cross-references been provided? A see should direct the reader to a different term expressing the same concept, such as “Clemens, Samuel. See Twain, Mark” or “aerobics see exercise.”
A see also should guide the reader from a complete entry to the related entries for more and different information. Examples: “Mammals: 81, 85, 105; see also names of individual mammals “astronomy 12-14, 56, 68. See also galaxies; planets.”
Are the subheadings useful? In the example below,
a) The page ranges are extensive
b) The subheading “problems with Republicans” may be too general
problems with Republicans, 1-32
Are subheadings concise, with the most important word at the beginning? For example, not:
and relationship to Federal Reserve bank
Federal Reserve regulations
Unnecessary words and phrases like “concerning” and “relating to” and proliferation of prepositions and articles should be avoided.
Is the number of subheadings about right? More than one column’s worth is probably too many. Are subheadings overanalyzed? Could they be combined? For example, could “dimensions” be substituted for “height,” “width” and “length”? Or should some subheadings become main headings with their own subheadings instead?
Do subheadings have more than five to seven locators? If more, they should either be broken down into sub-subheadings or be changed to main headings.
Is the type large enough to be easily read? Do the index pages look open and not crowded?
Are the main headings and subheadings) and sub-subheadings, if any) distinguished from each other?
Is the organization— whether alphabetical, chronological, or other— accurate, clear, and consistent?
When an entry’s subheadings are continued from a right-hand page to a left-hand page, the main heading should be repeated, followed by the word continued in parentheses. Depending on the size of the pages, continued headings might be appropriate for continuations from left to right pages, or even from left to right columns. Are they present?
Preferences for punctuation between main headings and their subheadings and see and see also cross-references will vary from publisher to publisher. This discussion features several acceptable variants. The important thing is that the punctuation style be clear to the reader and consistent. Is it?
Locators (Page References)
Are the locators accurate? Check a sample of entries to see.
When locators include roman numerals or volume numbers, does the typography make the usage clear?
For the reader’s convenience, many subheadings should be double posted—that is, they should exist as main headings too. For example: “Cats: Siamese” and “Siamese cats.” Has this been done? Double postings should, of course, have the same locators. Do they?
Length and Type
Is the index length adequate for the complexity of the book? An index should be three to five percent of the pages in the typical nonfiction book, perhaps five to eight percent for a history or biography, and more (15-20 percent) for reference books.
Is there a need for more than one type of index? For example, in addition to the usual subject index, perhaps a separate name or place index is called for. If so, is there one?
For More Information
- The Chicago Manual of Style, 16th edition, chapter 16, University of Chicago Press, 2010.
- Indexing Books, 2nd Edition, Nancy Mulvany, University of Chicago Press, 1995.
- ASI publications. See www.asindexing.org.
Please note: these are general guidelines and it is wise to evaluate each index according to the individual requirements and limitations of each project.