Determining the optimal session interval for transaction log analysis of an online library catalogue

Abstract

Transaction log analysis at the level of a session is commonly used as a means of understanding user-system interactions. A key practical issue in the process of conducting session level analysis is the segmentation of the logs into appropriate user sessions (i.e., sessionisation). Methods based on time intervals are frequently used as a simple and convenient means of carrying out this segmentation task. However, little work has been carried out to determine whether the commonly applied 30-minute period is appropriate, particularly for the analysis of search logs from library catalogues. Comparison of a range session intervals with human judgements demonstrate that the overall accuracy of session segmentation is relatively constant for session intervals between 26 to 57 min. However, a session interval of between 25 and 30 min minimises the chances of one error type (incorrect collation or incorrect segmentation) predominating.