Putting a Librarian's Face on Search

When you do a search on the University of Michigan Library's web site, you get not only results from the catalog, web site, online journal and database collections, and more, you also get a librarian who is a subject specialist related to your search term. While the matching is not perfect, it provides a human face on search results.

So, for example, if you search for "Kant," in addition to books and databases, you also get the subject specialist librarians for humanities and philosophy. A search for "Jupiter," you get the subject specialists for Astronomy & Astrophysics and Humanities (after all, we don't know if you're searching for the planet or the Roman deity). When we can't make a reliable match to a subject specialist, we provide a link to Ask a Librarian, our reference service.

How does the matching work?

The University of Michigan library has long maintained a database of Library of Congress Call Numbers and "Academic Disciplines" -- which is what we call our subject taxonomy. (You can see it in action in the site's Browse function.) These categories broadly mirror the schools and departments at the University of Michigan. Librarians have assigned Library of Congress call numbers to each academic discipline. This mapping was originally done for our New Books tool so that students and faculty could find out when a new book related to their area of study was acquired by the library. A single call number can be assigned to multiple Academic Disciplines, so a given book could appear in multiple places. In a site search, we do a special query of the library catalog behind the scenes and get the first 100 catalog results (sorted according to the catalog's relevance ranking algorithms). We sort those results into Academic Disciplines. If more than 25 items are in a single Academic Discipline, we include the subject specialist responsible for that particular area. (We set the threshold at 25 matches to help ensure a relevant match, but a librarian specializing in the "wrong" subject is arguably better than no librarian at all.) We make the call number-to-academic discipline mapping available on our site at http://www.lib.umich.edu/browse/categories/. There is also an XML version of the mapping free for all to use or adapt.


on July 26, 6:30pm

Very neat, thanks for sharing your technique, and your mappings too. How often/how much work is it to keep those LCC mappings up to date, are you constantly tweaking them, or is it pretty much done and good with only very occasional tweaking?

on July 26, 6:32pm

and have you considered adding this to your actual individual searches, catalog search for instance? How much use does your "meta-library-search" get compared to individual things like catalog? (Oh, and also, as always, consider a C4LJ article!)

Ken Varnum
on July 27, 8:39am

The call number mappings are fairly stable. The main work was setting them up; maintenance is a fairly small workload. Of course, with the scope of LC and the interdisciplinary nature of many of the Academic Disciplines, minor adjustments do come up from time to time. We've talked about putting the librarian in the catalog search, but have so far opted against it; I've been thinking about reopening that discussion lately, though, as I think it would add value. In terms of searches from the "Search" area on the library web site, the vast majority are done without changing targets. The top 10 permutations (since April 16, when we started tracking this) are as follows: MLibrary (All): 223113 searches (80.34%) MLibrary (Online Journals): 11579 searches (4.17%) MLibrary (Mirlyn): 8152 searches (2.94%) MLibrary (Search Tools): 6396 searches (2.30%) Articles (General Interest): 5726 searches (2.06%) Catalog (Keywords): 4832 searches (1.74%) Catalog (Title): 3072 searches (1.11%) MLibrary (Website): 1595 searches (0.57%) Articles (Social Sciences): 1430 searches (0.51%) Catalog (Author): 1349 searches (0.49%) Catalog searches done in Mirlyn (the catalog) on a daily basis outnumber the MLibrary searches done on the web site by about 3-1 on a typical day (6000 vs. 2000 for a normal weekday).