Many publishers and technology experts are foregoing including indexes in web, eBook, and other electronic products. At times this is understandable, after all indexing the entire content of the World Wide Web is not humanly possible.
However, when a book is put onto eBook platforms, when journal articles are loaded on a web site, there is no excuse for not including an index. The rationale usually given is that full text searching is available and so indexes are needed, are obviated by the technology, or are obsolete in this new electronic landscape.
“... trying the usual search keywords, and getting the usual mountain of junk ... was like combing through stellar radiation for signs of extraterrestrial life.” — Lev Grossman, 2011
If what is being searched for is a very discrete (and often unique) word or term, then searching may find what is being sought for instance, IRS Form 941 or Mark Twain. Adding more words to the search can narrow down the result set.
In fact this is not the case for various reasons:
- Concepts and terms of art are slippery because English has so much ambiguity, for instance search for vessel, do you mean a boat, ship, a vase, or a bowl. Sometimes the concept is represented by words in the text but the words of the concept itself are not there explicitly.
- Indexes often lead to the desired information more quickly (see the study noted below). With searching, a results set is presented and each result must be viewed to see if it is the information or a red herring or false positive.
- Indexes often provide useful "drill down" information. A main heading may be followed by a subheading display breaking down the subcategories of information leading to the user selecting a meaningful link.
- Indexes are usually ordered in an alphabetical array and adjacent main headings don't necessarily have similar meanings. However, this does happen and may be of interest to the browser (the person not the software). Additionally the serendipitous effect of seeing other headings in the index may pique the interest of the brower leading to other information being found that was unexpected but useful or interesting.
Little research has been done on this issue. So quotations and thoughts have been presented. For these and other comments on this topic, click here. One study was done showing indexes were superior to searching by BNA, Inc.