Experts' estimates of task duration in software development projects

This paper reports a case study of how accurate were experts' subjective estimates of the durations of tasks in a software project. The data available included the estimated task durations given by experts and the subsequent actual duration times. By looking at the results of the case study, the paper shows that although the majority of tasks are overestimated, the mean error is an underestimate of about 1%. The experts however could do even better by taking more cognisance of the number of subtasks that make up a task and hence use the WBS at a lower level when they are estimating durations.