M. Oivo and S. Komi-Sirviö (Eds.): PROFES 2002, LNCS 2559, pp. 383-397, 2002.  Springer-Verlag Berlin Heidelberg 2002 Improving Estimation Practices by Applying Use Case Models Bente Anda 1 , Endre Angelvik 2 , and Kirsten Ribu 1 1 Simula Research Laboratory P.O. Box 134, NO–1325 Lysaker, Norway {bentea,kribu}@simula.no 2 Mogul Norway Drammensveien 134; NO-0277 Oslo, Norway endre.angelvik@mogul.com Abstract. An estimation method based on use cases, the use case points method, has given promising results. However, more knowledge is needed about the contexts in which the method can be applied and how it should be adapted to local environments to improve the estimation process. We applied the use case points method to several projects in a Scandinavian software development company as the first activity in a software process improvement project on improving estimation. The second activity of the improvement project was to conduct interviews with project managers and senior developers about how to obtain continued and more widespread use of the method in the company. Based on the interviews, we propose a tailored, potentially improved version of the method and suggest how estimation practices can be improved by applying it. We believe that these experiences may be of interest to other companies that consider applying use case models as part of their estimation practices. 1 Introduction A use case model describes the functional requirements of a system to be constructed, and use case models are frequently used as input to the process of estimating software development effort. An estimation method based on use cases, the use case points method, was introduced by Karner [9]. This estimation method has been evaluated in several software development projects with promising results [2,3,12]; it was considered easy to use and performed similar to or better than teams of very experienced software developers. Nevertheless, more knowledge is needed about how to apply the method and tailor it to a specific organization. We evaluated the use case points method on three projects as the first activity in a software process improvement project on improving estimation in a Scandinavian