  According to a study of The Standish Group International, 44% of software
projects cost more and last longer than expected. More accurate the effort
estimation is; the better the enterprise gets organized and the more the
software project respects the commitments on budget, time and quality.
Enhancing the accuracy of effort estimation remains an ongoing challenge to
software professionals. Several factors can influence the accuracy of effort
estimation, namely the immaterial aspect of information system projects, new
technologies and the lack of return on experience. However, the most important
factor of cost and delay increase is software risks. A software risk is an
uncertain event with a negative consequence on the software project. In this
article, we propose a methodology to take into account risk exposure analysis
in the effort estimation model. In the literature, this issue is little
addressed and few approaches are investigated. In this research work, we first
present an overview of these approaches and their limits. Then, we propose an
effort estimation model that improves the accuracy of estimation by integrating
software risks. We finally apply this model to a case study and compare its
results to the results of a classic model.
