A discussion of statistical testing on a safety-related application

Safety-critical and safety-related systems are increasingly based, at least partially, on the use of software or logic components. High integrity claims are usually placed on these systems, which means that their probability of failure during operation should be below a specified level in order to ensure that risk of operation is sufficiently low. All this implies that some knowledge needs to be gained on the dependability of these systems or components in actual field use. Dependability assessment methods for software are not as well established as for hardware. Currently, formal proofs and statistical testing methods provide the only methods that have the potential to assess software dependability quantitatively. The present paper explores the applicability of statistical (software) testing (ST) to the example of a real safety-related software application. It discusses the key points arising in this task and highlights the unique and important role ST can play within the wider task of software verification.