Abstract
Safety-critical software systems need to meet exceptionally strict standards in terms of dependability. Best practice to achieve this is to follow and develop the software according to domain specific standards. These standards give guidelines on development and testing activities. The challenge is that even if you follow the steps of the appropriate standard you have no quantification of the amount of faults potentially still lingering in the system. This paper presents a way to statistically estimate the amount of undetected faults, based on test results.