Abstract
Whether a software project will succeed is strongly dependent on the pre-project estimation activities. It is because the framework of a project is determined at the estimation stage. Although in these days active discussions have been done for estimation technologies and effective data accumulation, estimation is still evaluated with implicit knowledge such as experience or intuition in many cases. Especially for enhance projects, reliable estimation method has not been established. Also in enhance projects, some risk factors which can be disregarded in development projects should be considered. This paper studies an approach to eliminate ambiguity and improve rationality, objectivity, and validity of the estimation for the enhance projects.
