Impact Theories: Trends in Off-site Shelving Facility Use Zack Lane, ReCAP Coordinator, Columbia University Libraries | Colleen Major, Networked E-Resources Librarian, Columbia University Libraries ReCAP (Off-site Shelving): Libraries increasingly rely on off-site shelving to solve space problems. In 2002, Columbia University Libraries, NYPL and Princeton University opened ReCAP (Research Collections and Preservation), a shared high-density shelving facility. It now serves as Columbia University Libraries largest collection with 3.09 million volumes. EDD Requests: Speed and convenient access to off-site collections are high priorities for Columbia. Physical requests are normally delivered in one business day; patrons may also request Electronic Document Delivery (EDD), in which staff scan and deliver articles by . Data trends: Data reflect a sharp decline in the total number of EDD requests. The decline trend is pronounced for science subject collections compared to non-science collections. This poster session presents an investigation of impact theories about correlation and causality related to EDD request trends. Hypotheses: Increased online availability of electronic journals correlates with the decline trend of EDD requests. Local initiative Science Fast-Track also contributed to the decline. Patron preference has an impact on total number of EDD requests. Conclusions: 1) Online availability of full-text backfiles shows a positive correlation to a decrease in EDD requests. Backfile acquisition of high-use titles is actionable result. 2) Local initiative Science Fast-Track had no correlation to a drop in EDD request volume. Neither the service model nor statistics displays a relationship. 3) Patron use data according to group is inconclusive. Researchers plan to follow-up results with alternate analysis, looking specifically at mode of discovery to resultant information request. 1) Total Number EDD Requests2) Breakdown of Science / Non Science 3) Size of Collections at ReCAP 1)Data show a decline in total number of EDD requests starting after FY06. 2)The total volume of science collection EDD requests compared to non-science. Science collections are defined by owning library: Biology, Chemistry, Engineering, Geology, Geoscience, Physics, Psychology and Science. 3)The size of ReCAP collections continually increase. CUL currently transfers 300,000 volumes every financial year. 1) Rate of Physical Delivery, Science / Non Science 2) Rate of EDD, Science / Non Science ReCAP collections are accessed by physical delivery or EDD. The majority of requests are physical delivery. The target request rate for ReCAP collections is 2.0% per year. The request rate is a ratio of request volume and size of collection at ReCAP. Rate graphs are divided by month. Variation is due to CU’s academic calendar year. The rate of physical delivery is similar for both science subject and non-science collections. The request rates for EDD vary between science subject and non- science collections. Since mid- FY04, the rate of EDD request for science collections has declined. Non-science collection EDD requests also experienced a rate decline in FY08. Data sets are extracted from CUL’s request mechanisms. Requests are placed in CLIO, CUL’s OPAC. Use by patron group was analyzed from both Voyager circulation statistics and EDD request data. Circulation of onsite collections from the main library circulation desk in FY08. Largest user group is undergraduates. Variation is due to CU’s academic calendar year. Circulation of offsite collections from the main library circulation desk in FY08. Grad students and faculty outnumber charges to undergraduates. Accurate data on population size is not currently available to researchers. Data is only accurate for previous 12 months, preventing historical analysis. Faculty represent larger proportion of EDD users than for physical access. Total number of requests for the top 100 EDD high-use titles. Researchers split the titles between those with archival full text available online and those in print only or current years of publication available in full text. 38 of the 100 have full text available online; 62 were print only or had current years online. EDD requests from offsite collections in FY08 for top 100 high-use titles. Data for EDD related requests mirrors that of off-site collections in general. There is no remarkable correlation between patron group and high-/low-use material. Researchers plan to explore user preference of discovery mechanism Top 100 EDD High-Use Titles: a) Archival Full Text b) Print Only/Current Years Online. EDD requests from offsite collections in FY08. Circulation of OFFSITE Collections Circulation of ONSITE Collections Top 100 EDD High-Use Titles by Patron Group