A Simple Stochastic Model for Library Loans

A simple stochastic model for the borrowing of books from a library collection is proposed which explains some observed circulation frequency distributions. Use of the model requires the specification of just two parameters which may be calculated from the circulation statistics for a fixed period of time. These allow one then to make predictions regarding the patterns of likely future usage, and should assist therefore in determining the impact of any proposed relegation policy. The article is illustrated with data from the library of the University of Sussex, the Wishart Library of the University of Cambridge and from the published University of Pittsburgh study. In the latter case our conclusions differ from those of the original investigators.