Measuring the Cost of Software Quality of a Large Software Project at Bombardier Transportation: A Case Study

In a competitive world, it is important to measure and improve the performance of software engineering processes and imperative to identify and eliminate rework that could have been avoided. The cost of software quality is one measure of the performance of software processes. It comprises the total cost associated with the prevention, appraisal, and correction of the anomalies in a product. A measure of the cost of software quality was performed by the software development group at Bombardier Transportation, a division of Bombardier Inc., located in Québec, Canada. A team of 15 software engineers developed the software to control the subway of a large American city. A project to measure the cost of software quality was carried out in four stages. A set of 27 classification rules was developed, and weights were assigned to each project task. More than 1100 software tasks were analyzed on a project totaling 88,000 hours. The measurements show that the cost of software quality represents 33 percent of the overall project cost. The cost of rework, or the cost of correcting anomalies, is 10 percent, the cost of prevention is 2 percent, and the cost of evaluation is 21 percent of the total development cost.