The paper briefly describes sequential sampling and explains how such sampling procedures can be integrated into a software testing strategy to provide benefit. Using first-pass failure rate, (a simple software testing metric), as a quality indicator, the authors show theoretically and empirically how sequential sampling plans can be used to establish a mechanism with known statistical confidence/risk which allows for decisions to stop testing when product quality either meets the target or is worse than the expectation. Quality assessment, as well as quality certification roles, can be addressed. When sequential sampling is coupled with other simple statistical techniques, information can also be provided to help identify fault prone areas. Data from releases of the 5ESS Switch project are used in several examples to validate the usefulness of the techniques.>

Code inspections have been used on the 5ESS switch project since 1983. Beginning with a training program for all the developers involved in the project, code inspections have improved with each new 5ESS switch generic. Variations on a standard SQC (statistical quality control) technique, the control chart, have been used to track the metrics indicative of the effectiveness of code inspections. Parameters used in the computation of these metrics include the preparation effort, inspection time, number of inspectors, the size of the inspected unit of code, and the number of errors found at the inspection. It is noted that the exact form that these control charts have taken has evolved and improved with experience.>