Sequential Analysis: A Methodology for Monitoring Approval Plans

Sequential analysis is a statistical method based on drawing sample items one at a time, with a decision at each stage whether further sampling is necessary to reach a conclusion. This methodology is shown to provide a convenient and appropriate method for investigating the performance of a library approval plan. The sequential approach minimizes the investment in staff time, by delaying, until a title is chosen for the sample, the determination of its status in the approval plan. Application of the methodology at an academic library is reported in detail, and adaptations to other library situations are explained.