Abstract
In this paper we present a methodology for uncertainty analysis of the software operational profile suitable for large complex component-based applications and applicable throughout the software life cycle. Within this methodology we develop a method for studying the sensitivity of software usage to changes in the operational profile based on perturbation theory. This method is then illustrated on three case studies: software developed for the European Space Agency, an e-commerce application, and real-time control software. Results show that components with small execution rates are the most sensitive to the changes in the operational profile. This observation is very important due to the fact that rarely executed components usually handle critical functionalities such as exception handling or recovery.