Software is used everywhere in society, and is assuming responsibility for the systems that support the foundation of society. Nevertheless, software vendors are struggling to guarantee quality. To solve the problem, NEC Corporation devised a quality management method called "Software Quality Accounting," which has been built up and operated for over 30 years. NEC has been able to reduce and maintain the number of post-release defects to less than 5%. Quality accounting is based on the idea that defects should be seen as "debts." It is more economical to pay off debts early, before they grow...