Improving the accuracy of project estimates at completion using the Gompertz function

Synopsis A nonlinear regression-based growth model based on the Gompertz S-shaped function is used to forecast cost profiles for ongoing projects experiencing overruns. Based on the standard approach to earned value management and earned schedule, a simple linear expression is derived for the forecast of the duration estimate, and the theoretical formula is validated by application to case projects. The model’s predictions are shown to be accurate, stable and reliable. We conclude with practical guidance for project managers. Relevance for practice and education An effective method of duration and cost forecasting is established and validated. The duration and cost error formulas are quite simple and practically useful to project management practitioners during project monitoring and control. Research design Using the standard definition of the earned schedule and Gompertz curve cost profiles, estimates of the final duration are found by using regression curve fitting on the first and last available earned value data. Validation is conducted on many synthetic project data sets. Main findings It is found that a simple two-point curve-fitting estimation formula is effective in predicting the duration of an ongoing project. Research implications This research broadens discussions on accuracy on nonlinear duration and cost estimates of ongoing projects, using different cost profiles and the standard definitions of the earned schedule.