Analysis of external and internal interlibrary loan requests: aid in collection management.

The analysis of 60,779 external interlibrary loan requests for copies of periodical articles from the collection of Erasmus University Medical Library in 1988 is described. The study was used for planning the length of backruns to be retained due to space limitations that forced the disposal of older volumes. More than 50% of requests were for the most recent two-year period, and 90% of requests could be filled with a twenty-year run of periodicals. In 1989, 4,157 internal requests were received for periodicals not owned; these were analyzed to determine those most commonly requested. Prior to subscribing, new titles were reviewed as to price, bibliometric indicators, number of requests, length of backfile, and the number of requesting departments. The Library Advisory Board decides on cancellation or purchase of periodicals; the elements considered are described.