The Depths of Cost-per-Use: Historical Context and Applications

Practicing librarians, library science researchers, operations researchers, and economists have documented their extensive efforts to ensure that libraries serve users effectively and efficiently. The measures and methods used have, in some ways, grown substantially more complex and sophisticated. Such tools include development of statistical models describing the use, and predicting future use, of resources (largely books and journals), as well as incorporating more variables to better explain the use. The cost-per-use metric, however, has become ubiquitous and nearly universal for evaluating resources, especially renewable resources such as journals and databases. Composed of only two factors, cost and use (and, by implication, time), this measure provides context missing from either metric alone, yet is simple enough for most practicing librarians and the library stakeholders to instantly comprehend. This article provides a background to the forces that led to the development, use, and gradual acceptance of this metric, and concludes with a case study of its application in different collection development decisions at the author's institution.