One of the findings of the custom collection overlap studies we have done is that rareness is common: there are low overlap levels between collections. The comparison of collections has become a topic of stronger interest as libraries look at mass digitization and shared storage facilities, and pressure on space continues. These are examples of 'collective collection' issues, as organizations consider the disposition of collections within inter-institutional policy environments.
Over on hangingtogether.org, Günter Waibel describes some work that he and Brian Lavoie have been doing looking at the collective collection of NYARC (the New York Art Resources Consortium, a group of four art museum libraries). Günter presents some early findings; a fuller report will appear later. Looking at unique titles in the aggregate collection, the majority are held by only one library, and a very small number are held by all four.
Under the auspices of a planning grant sponsored by the Mellon Foundation, the four art museum libraries listed above formed the New York Art Resources Consortium (NYARC) to explore deep collaboration. (Three of the four have already announced a joint ILS [pdf] project.) We engaged NYARC in the analysis project to supply the art museum libraries with the business intelligence they need to make informed decisions about the nature of their collaborative efforts. The analysis determines the size of the collective NYARC collection, the extent of holdings overlap as well as uniquely held materials. The project also compiles statistics about specific types of materials the consortium holds a special interest in, such as auction catalogs, exhibition catalogs and serials. A comparison of the NYARC holdings to a set of three local research libraries (New York Public Library, New York University and Columbia University), as well as a west-coast peer institution (Getty Research Institute) provides additional context for the findings. [hangingtogether.org » Blog Archive » NYARC: One for all, and all for one?]
An interesting aspect of this work is that it was carried out on data from the RLG union catalog.