Eliminating over-confidence in software development effort estimates

Abstract

Previous studies show that software development projects strongly underestimate the uncertainty of their effort estimates. This overconfidence in estimation accuracy may lead to poor project planning and execution. In this paper, we investigate whether the use of estimation error information from previous projects improves the realism of uncertainty assessments. As far as we know, there have been no empirical software studies on this topic before. Nineteen realistically composed estimation teams provided minimum-maximum effort intervals for the same software project. Ten of the teams (Group A) received no instructions about how to complete the uncertainty assessment process. The remaining nine teams (Group B) were instructed to apply a history-based uncertainty assessment process. The main results is that software professionals seem to willing to consider the error of previous effort estimates as relevant information when assessing the minimum effort of a new project, but not so much when assessing the maximum effort! © Springer-Verlag Berlin Heildelberg 2004.