Revisiting ÔobsolescenceÕ and journal article ÔdecayÕ through usage data: an analysis of digital journal use by year of publication David Nicholas a, * , Paul Huntington a,1 , Tom Dobrowolski a,2 , Ian Rowlands b,3 , Hamid R. Jamali M. a,1 , Panayiota Polydoratou b,4 a SLAIS, University College London, Gower Street, London WC1E 6BT, UK b Department of Information Science, City University, London EC1V 0HB, UK Received 27 September 2004; accepted 3 March 2005 1. Introduction The publication age or date of documents used (or not used) has long fascinated researchers and prac- titioners alike. Much of this fascination can be attributed to the weeding opportunities the data is thought to provide for libraries in their never-ending battle to find the space to accommodate their expanding col- lections. In general journal article age studies have shown an initial increase in use/citation, then a gradual or sharp decline, depending on the discipline concerned. This characteristic has been termed obsolescence or decay and was largely measured, in the absence of accurate journal usage/borrowing data, by citations. In the sciences the decay rate was shown to be the greatest. This was largely put down to the rapid obso- lescence of much scientific content. New research findings, methods or ensuing events rendered the material obsolescent. Of course, when reviewing the data we need to be reminded of the fact that citation studies reveal ‘‘use’’ by authors, whereas library loans or downloads represent actual use by readers, and it is read- ers that libraries and digital libraries principally target. Clearly the fall of in use with time must have also been a function of the way that libraries arranged their material (in reverse chronological order); a lack of time and patience will inevitably result in readers abort- ing their searches after a few years and those few years will be the most recent ones. Similarly, it must also have been a function of the difficulties of searching hard-copy back volumes/issues in libraries over time. 0306-4573/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ipm.2005.03.014 * Corresponding author. Tel.: +44 20 7679 2107; fax: +44 20 7383 0557. E-mail addresses: david.nicholas@ucl.ac.uk (D. Nicholas), paulh@soi.city.ac.uk (P. Huntington), whtom@interia.pl (T. Dobrowolski), ir@soi.city.ac.uk (I. Rowlands), h.jamali@gmail.com (H.R. Jamali M.), dy661@soi.city.ac.uk (P. Polydoratou). 1 Tel.: +44 20 7679 2107; fax: +44 20 7383 0557. 2 Tel.: +48 609 713 527. 3 Tel.: +44 20 7040 8389; fax: +44 20 7040 8584. 4 Tel.: +44 20 7040 3905; fax: +44 20 7040 8584. Information Processing and Management 41 (2005) 1441–1461 www.elsevier.com/locate/infoproman