Use cases modeling and software estimation

Abstract

This article discusses software size/effort estimation by the Use Case Points method (UCP). It is based on the experience accumulated during deployment of the UCP in a software development department of a major financial institution. Typical for such an environment is that software is developed on top of existing applications, and that there are significant differences between projects in business domains, scope, size, complexity, project management details, etc. In a previous article [3] an extension of the Use Case Points method, called UCPm, was described that addresses these issues.Due to their level, use cases make high-level estimation easier. However, this article, presenting a number of real world situations, demonstrates that to obtain reasonably accurate estimates we need to reflect in use case models some aspects of the existing application and of the current project. It also suggests some clarifications of the concept of use case transaction and outlines some ways to support use case models consistency within and across projects.