Rezaie, Manouchehrabadi & Shirkouhi (481) discuss the critical chain project management (CCPM), which was initiated in 1997 by Goldratt, referred to as the theory of constraint. Ever since, the CCPM has attracted substantial attention both in execution communities and the academic world. One of the leading controversial issues of the critical chain project management, which is a subject matter of many critics, is the manner it proposes for activity duration estimation. Rezaie, Manouchehrabadi & Shirkouhi (481) suggest a new-fangled technique for duration estimation of activities through estimating the level of uncertainty buried in each activity duration and after that taking out of safety periods related to this uncertainty. The validity or soundness of this proposed method, according to the authors, is measured by carrying out a computer simulation on a number of the test problems. Simulation analysis proves that the suggested technique yields schedules that are more dependable than the schedules established by first CCPM technique of duration estimation. Some of the crucial key terms discussed in this article include critical chain, theory of constraint, duration estimation and project scheduling. Critical chain, according to Rezaie, Manouchehrabadi & Shirkouhi (481) is the longest series of events through the project network following the resource contentions. Critical chain, in other words, is a group of tasks through which the project general duration is decided. The authors also discuss how time/duration estimation is a crucial matter of the critical chain. The authors discuss how Goldratt dedicated a substantial part of this research trying to explain the cause why safety periods cannot safeguard the projects intended dates against the doubt embedded in projects.
Rezaie, Manouchehrabadi & Shirkouhi (482) give numerical facts, which were not broadly discussed in Goldratt’s original work. They argue that Goldratt did not exactly specify any numerical distribution function, but assumed a right distorted distribution for every activity duration whereby there was a significant distance between 50% quantile and 90% quantile. They further talked about the propensity among individuals involved in time estimation to overrate the required time so that adequate safety period is put into the measures. The third section of the article, Investigating of Time Estimation Methods, analyzes the method proposed by the authors. The authors go deep into the explanation giving both quantitative and qualitative facts. Conveying the logic to the stakeholders might be difficult, and make individuals feel stress and nervousness (Rezaie, Manouchehrabadi & Shirkouhi 487). The authors simplify the subject through saying that people should realize that these projections are rough plus there are buffers that would balance in case, but the problem occurs because of unrealistic estimation of events. This is when buffers begin warning managers, and they, on the other hand, blame individuals working on events, so there could be better ways of eliminating safety times from events.
The final section of the article discusses the experimentation of the findings. In order to assess the competence of the suggested method for activity duration estimation, a simulation was carried out with the aid of the MATLAB 7.5 software on a PC (Rezaie, Manouchehrabadi & Shirkouhi 488). The findings proved that, in reality, the method proposed by Rezaie, Manouchehrabadi & Shirkouhi was more effective than the one proposed by Goldratt.
- Rezaie, Kamran, Manouchehrabadi, Bengrah and Shirkouhi, Nazari S. “Duration Estimation, a New Approach in Critical Chain Scheduling 2009”. Third Asia International Conference on Modeling & Simulation. IEEE Computer Society. Web. 6 April 2013.