COQUALMO (COnstructive QUALity MOdel)--formerly called CODEFMO--is an estimation model that can be used for predicting number of residual defects/KSLOC (Thousands of Source Lines of Code) or defects/FP (Function Point) in a software product. It can be applied in the early activities such as analysis and design, as well as in the later stages for refining the estimate when more information is available. It enables 'what-if' analyses that demonstrate the impact of various defect removal techniques and the effects of personnel, project, product and platform characteristics on software quality. It also provides insights into determining ship time, assessment of payoffs for quality investments and understanding of interactions amongst quality strategies.