Better Software Effort Estimation—A Matter of Skill or Environment?

Estimating the effort of software development is fraught with difficulties, and it is clear that effort should be invested in improving the accuracy and the reliability (consistency) of effort estimates, as well as the assessment of estimate uncertainty. However, it is less clear where to target such improvement efforts. We discuss the degree to which it is feasible to improve the expertise of the person(s) who estimate(s), and the environment in which the estimation is performed. The former hinges on what there is to say about the development of estimation expertise and the task characteristics of effort estimation. The latter hinges on what contextual support may be developed in terms of environment control and tools and methodology. We integrate several theories to make a framework for discussing software effort estimation and planning. On the basis of that discussion, we conclude that present guidelines almost exclusively concern the environment and its influence on broad psychological factors, that task-specific estimation expertise is too weak a signal in the noise of biases, and that strengthening this expertise requires new efforts in understanding the task-specific elements in software effort estimation and planning, as well as environmental measures (tools and methodologies) that support expert behavior and expert learning.