Software Development's Cone of Uncertainty

Software's Cone of Uncertainty is a model for understanding estimation uncertainty in software projects. Early in a project, specific details of the nature of the software to be built, details of specific requirements, details of the solution, project plan, staffing, and other project variables are unclear. Estimates inherently contain high uncertainty early in projects but this can be reduced once the project is underway. This whitepaper from Steve McConnell, Chief Software Engineer/CEO at Construx Software, introduces the concept of the Cone of Uncertainty and how reducing variability along the way can improve estimates and "narrow the Cone."