A New Statistical Software Reliability Tool M.A.A. Boon 1 , E. Brandt 2 , I. Corro Ramos 1 , A. Di Bucchianico 1 and R. Henzen 2 1 Department of Mathematics, Eindhoven University of Technology, Eindhoven, The Netherlands 2 Reﬁs System Reliability Engineering, Bilthoven, The Netherlands Abstract We describe a new statistical tool for software reliability analyses that we are developing. Existing packages for statistical analysis of software reliability data do not make full use of state-of-the-art statistical methodology or do not conform to best practices in statistics. Our tool has a Java based interface and uses the statistical programming language R (see www.r-project.org) for the statistical computations. R is open-source free software maintained by a group of top-level statisticians and is rapidly becoming the standard programming language within the statistical community. The tool has a user-friendly interface which includes features like autodetection of datatype and a model selection wizard. Keywords: software reliability, software testing, statistical models, R. 1 Introduction Successful testing processes require excellence in both software testing and management. In order to support well-founded decisions on issues like resource allocation and software release moments, quantitative procedures are indispensable. Since few testing processes have a de- terministic course, statistics is very often an appropriate part of such quantitative procedures. Existing tools for software reliability analysis like Casre and Smerfs 3 do not make full use of state-of-the-art statistical methodology or do not conform to best practices in statistics. Thus, these tools cannot fully support sound software reliability analyses. We decided to build a new tool that • uses well-documented state-of-the-art algorithms • is platform independent • encourages to apply best practices from statistics • can easily be extended to incorporate new models. In order to meet these requirements we decided to use Java for the interface and the statistical programming language R (see www.r-project.org) for the statistical computations. R is open- source free software maintained by a group of top-level statisticians and is rapidly becoming the standard programming language within the statistical community. In this paper we report on the status of our tool. Our tool is a joint project of the Laboratory for Quality Software (LaQuSo) of the Eindhoven University of Technology (www.laquso.com) and Reﬁs 1