Bursts and heavy tails of execution time in business processes

This paper investigates the phenomena and effects of heavy tails of execution time in business processes. We approached the heavy tails as a particular variation of business process execution, and analysed them from empirical data of its execution time. The features and possible causes of the heavy tails were investigated. A workflow simulation was conducted to simulate the heavy tails, in order to evaluate quantitatively their effects to business process performance. The simulation outcomes demonstrate that (1) even a heavy-tailed activity in a business process can cause large variation of end-to-end execution times of the process and (2) there are significant prediction gaps resulted by different assumptions of execution times between an exponential distribution and a heavy-tailed distribution.