Costs are the amount of money that is necessary to implement one or more software process improvement (SPI) methods. Costs are the expenses associated with applying, using, and exploiting SPI methods. Costs are the resources that are necessary to deploy and institutionalize SPI methods in a software organization or firm. Costs or cost factors consist of training, process development, and product development. Appraisal preparation, appraisals, product development, inspections, tests, and maintenance are major costs. Training refers to SPI methods that rely on formal classroom training as the principal delivery mechanism for the SPI method. Process development refers to SPI methods that require organizations to design and develop policies and procedures. Product development refers to SPI methods that require the development of special work products or project artifacts for projects. Appraisal preparation refers to SPI methods that necessitate advanced preparation by software project members. Appraisal refers to SPI methods that require a formal assessment or audit of activities and artifacts to verify their use. Product development refers to the costs of analyzing, designing, and coding software products using software effort models. The inspection cost factor consists of SPI methods that use the Software Inspection Process. The test cost factor consists of the costs of testing software products for all SPI methods. Finally, the maintenance cost factor consists of the total life cycle costs of all SPI methods. Some costs entirely consist of training. Some costs are associated with expensive appraisals and audits. However, most SPI methods have common costs such as...