North Carolina State University now lets you search its libraries’ collections using faceted classification.

Go to the libraries’ search page and search for any term. For example:

On the search page, enter “military music” (no quotes). It returns a straightforward list of works about military music. But, on the left of the search page are the facets under which the works on the returns list are classified, e.g. Topic, Format, etc. Under each of those is a list of the types available under that facet. E.g., Under Format we see there are 146 books and 16 DVDs about military music. (Think of a facet as a column in a database and the types as the contents of the cells in that column: At an online music site, a column might be Genre and the types might be rock, jazz, classical, etc.)

Under the Topic facet, click on “United States.” You are now shown a list of all the holdings about military music and the US. Notice that the list of facets on the left has changed. For example, DVDs have vanished from the Format facet because the libraries have no DVDs about US miliitary music. Faceted classification systems don’t show you impossible or irrelevant options. No dead ends, no branches without fruit.

Under the Era facet, click “20th Century.” We’re down to three results and the facet list has narrowed dramatically. For example, the Format facet only shows Books and E-Books.

Under the Genre facet, click on “Songs and music.” We’re down to three results and the facet list has narrowed dramatically. The Format facet is entirely gone because all three results are books.

Suppose, however, you decide the list of returns is too small. You’re willing to consider books about more than just the US. Toward the top of the page, on the left, the NCSU site shows you the facets you’ve selected already, with a little red X box next to each. Click on the X next to “United States,” removing it as a selection criterion. Not only does the list of returns expand, now a bunch of facets are back because they’re legitimate choices. Notice that you don’t have to walk back up the tree in the order in which you created it.

Why is this a big deal? Unlike parametric searches that let you enter specifications for your search, a faceted search doesn’t simply apply search criteria. Instead, a faceted classification system — in this instance, called a “guided navigation” system by Endeca, the company behind this implementation — the browsable interface changes with every choice so that it never shows you parameters that would result in an empty results list. So, you don’t have to keep randomly banging on it and then backing up, trying to find the one book you want, or the one left-threaded, chrome-plated, 15mm, philips-headed, round-capped screw you need as you build the specs for your new aircraft engine. And when it turns out there are no screws exactly like that, you can decide you could do without the chrome-plating, or the philips-headedness, until you get something that works. Endeca has a customer with a library of 25 million engineering parts for whom this type of interactive search is a tremendous time and money saver.

As Endeca will tell you, there’s another advantage as well: Faceted systems know a lot about their contents. That’s why they’re able to show you how many entries there are in each branch before you click on it. Endeca uses this information to build data reporting systems that let you click facets in and out, interactively revealing patterns that might otherwise have been hard to find. (Non-disclosure: I am not involved with Endeca, although I’m using them as an example in my book because I think what they’re doing is way cool.)

(Thanks to Peter Morville for the link, who also points to this thread about the implementation.)

[Tags: facetedClassification taxonomy EverythingIsMiscellaneous libraries endeca]

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