Wednesday, February 15, 2012

The Impact of Books

Effect of heavily-cited monograph
During a recent monographs deselection project, an astute librarian inquired whether a book's "impact factor" -- the number of times it has been cited in other books or journals -- might be invoked as a title protection rule. Impact factor, of course, is a concept much more highly developed for journals and conference proceedings than for monographs. Often described as a quantitative tool for evaluating journals, impact factor captures the frequency with which an article has been cited in a three-year period. At the journal title level, it captures the average number of citations per paper. Results are published annually in Journal Citation Reports. While not without controversy as a performance metric, impact factor is widely used as a shorthand indicator of article and journal quality.

Recently, an impact factor for books has begun to receive some overdue attention. In late 2011, Thomson Reuters introduced the Book Citation Index, available through its Web of Knowledge platform. Despite its bold taglines of "putting books back into the library" and "completing the research picture", it represents a fairly modest beginning. By December 2011, it was projected to include 30,000 titles, with a plan to add 10,000 per year. The Thomson Reuters site describes a careful selection process, and highlights improved discovery and citation navigation as the Index's primary attributes. But there is a clear implication that these are important monographs in their respective fields.

This implication is not without controversy. Metrics such as citation analysis raise the hackles of some researchers, especially in the humanities and social sciences, as shown in a lively exchange of comments following this article from Times Higher Education: "Monographs finally join citations database."  On October 13/14, 2011, a Mr Flannigan let it be known that:
"The field of citation counting isn't a 'field' in any intellectual sense. It's a shortcut; an attempt to evade engagement with intellectual content and reduce everything to the logic of a spreadsheet."
 "I don't doubt that some disciplines might benefit from citation counting. But I'm sick of scientists imposing their methods onto non-cognate disciplines and demanding that everyone else fall into line."
Several recent articles further explore book and even chapter-level impact using sources other than BCI. "Assessing the citation impact of books: the role of Google Books, Google Scholar, and Scopus", published in November 2011, examines whether these databases can provide "alternative sources of citation evidence", and specifically looks at references to and from books. Planned data mining of the Hathi Trust corpus may open up some new avenues. A 2006 account of a pilot project for the Australian Council for the Humanities, Arts, and Social Sciences tests the extension of citation analysis to books in history and political science:

Source:Linda Butler, Council for the Humanities, Arts, & Social Sciences
We'll follow up on these and other recent works on "bibliometrics" in a subsequent post. (Mark your calendars for that!) For now, let's assume that book impact factors are worth some consideration in decisions about storage, withdrawal, and retention.

As monographs are considered for deselection, there is often a desire to exempt titles that appear on "authoritative" lists or core lists, regardless of whether those titles have been used. Examples include titles listed in Resources for College Libraries or as CHOICE Outstanding Academic Titles, or on discipline-specific accreditation lists. Clearly, titles listed in the Book Citation Index could fall into this category, and might be considered candidates for retention irrespective of other considerations, even as the debate about citation analysis continues.

There is one very practical problem, however. Book Citation Index, as currently constituted, is limited to books with copyright dates in the current year plus 5 previous years in the Sciences, and current year plus 7 previous years in Social Sciences and Humanities. As this is written in early 2012, then, coverage includes:
  • Sciences: books published in 2007 or later
  • Social Sciences & Humanities: books published in 2005 or later
To date, deselection criteria in the projects supported by our firm Sustainable Collection Services have focused on titles published or acquired before 2005--sometimes much earlier. The universe of titles being considered for withdrawal and the universe of most-cited titles in Book Citation Index at present do not overlap at all. For now, impact factor simply cannot play a role in deselection decisions. The relevant data does not yet exist in any consolidated form.

As the list of titles grows over time, it will become more relevant. But the role of book impact factor in deselection will emerge only as titles published in 2005 and later begin to appear on withdrawal candidate lists. The utility of the impact factor will grow incrementally; under the Book Citation Index model, 10,000 additional titles will be available for analysis each year. In five or ten years, this may be an important data point. But not quite yet. In fact, it may not be necessary at all, since presumably highly-cited books would tend to receive more use. And in deselection decisions, use trumps most other considerations.

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