Christopher Galbraith
Padhraic Smyth


In this paper we investigate the application of score-based likelihood ratio techniques to the problem of detecting whether two time-stamped event streams were generated by the same source or by two different sources. We develop score functions for event data streams by building on ideas from the statistical modeling of marked point processes, focusing in particular on the coefficient of segregation and mingling index. The methodology is applied to a data set consisting of logs of computer activity over a 7-day period from 28 different individuals. Experimental results on known same-source and known different-source data sets indicate that the proposed scores have significant discriminative power in this context. The paper concludes with a discussion of the potential benefits and challenges that may arise from the application of statistical analysis to user-event data in digital forensics.