Age & Currency - Concepts
Publication dates may also be used to measure collection age. How this data is interpreted will depend on the mission of the library as a whole or on the purpose of a particular subject area. For example, while demand and space may call for the weeding of older collections in some libraries or within particular collections (e.g., undergraduate collections), it would be contrary to their mission for research libraries to weed old works. So, while the books in one library’s collection may be described as "outdated," the same books in another library would be considered "core."
On the other hand, all libraries need to keep their collections up-to-date. This data can help determine the currency of collections. For example, perhaps the overall number of books in engineering is large, but that number really reflects a high amount of purchasing prior to 1998. Unlike publication dates, the overall collection size reveals nothing about current acquisitions or whether or not the collection is dated. Publication dates can also help uncover small and interesting sub-collections, for example, a small sub-collection of German language literature of the 18th century within a very large general literature collection.
Age & Currency - Interpretations
In using the publication date to measure the age of collections, the following types of questions can be answered:
Based on an analysis of the average age, what subject collections appear to be in need of updating?
Have collecting patterns changed? Assuming no massive retrospective buying occurred, it is possible to trace a trend. For example, in the early decades of the 20th century, European theater may have been the focus of collection building in Performing Arts. What about in the last thirty years (1970 to 2000)? Has there been a de-emphasis on European theater and in increasing shift toward American theater?
In which decades is the collection strongest? How does that compare with peer institutions?
Among the oldest collections, which subjects are most prominent? Do the numbers appear to support the library's long-held belief that the strength of the Art monograph collection lies in books about painting published during the 1920's? Is that still true?
