The analogy method belongs to the methods of effort estimation. For this purpose, a comparison of the project to be estimated with similar, completed projects takes place. An analysis of the differences establishes similarities and differences between the projects with regard to the most important influencing factors (project organization, development environment, metrics, etc.). This is followed by an assessment of these in terms of effort and productivity. The estimation accuracy depends on how well one knows the project to be estimated (functional specification) and on the experience in the correct selection and estimation of the influencing factors in the deviation analysis. The basis of the analogy method is extensive experience with similar, completed projects.