Realistic Time Estimates Revisited



By Dr. Kenneth Smith, PMP

Honolulu, Hawaii
Manila, The Philippines



A recent (June 2020) PMWJ article by Dr. Benedict Amade[1] addressed the fact that PERT — Project Evaluation and Review Technique — is a fundamental tool for determining a schedule, but lamented that most software do not perform computations on the probabilities of completing a project; and presented a computerized template to resolve the problem.

The research, writeup, application and end product are commendable; but did not go far enough.  An underlying issue — namely that the PERT formula per se is fundamentally flawed — was not addressed or resolved.  My Oct 2019 PMWJ article[2] addressed that issue, presented a modification to the PERT formula to encourage more realistic consideration when scheduling, and illustrated a user-friendly template highlighting the difference.

However, after reading Dr. Amade’s article and reviewing my own, I realized that I too had not paid sufficient attention to the needs of the client, manager or scheduler to know the probability of completing a project or an individual activity, and be able to appreciate its impact.  Consequently, I reworked my template to facilitate consideration of these aspects, as illustrated on the following page.

This upgraded template not only provides users with the probabilities of any unrealistic deadlines they may consider, but also highlights the extremely low probabilities of traditional ‘Optimistic,’ ‘Most Likely’ or even ‘PERT’ duration estimates. This revelation reemphasizes the reason why traditional approaches to estimating schedules have had such a dismal record, and are predestined to fall short of expectation unless & until more reasonable targets are adopted to address this pernicious problem.


To read entire article, click here


How to cite this article: Smith, K. (2020).  Realistic Time Estimates Revisited, PM World Journal, Vol. IX, Issue VIII, August. Available online at https://pmworldlibrary.net/wp-content/uploads/2020/07/pmwj96-Aug2020-Smith-realistic-time-estimates-revisited.pdf



About the Author

Dr. Kenneth Smith

Honolulu, Hawaii
Manila, The Philippines


Dr. Kenneth F. Smith has been a project management consultant for ADB, the World Bank, and USAID for decades. He earned his DPA (Doctor of Public Administration) from the George Mason University (GMU) in Virginia and his MS from Massachusetts Institute of Technology (MIT Systems Analysis Fellow, Center for Advanced Engineering Study). A long-time member of the Project Management Institute (PMI) and IPMA-USA, Dr. Smith is a Certified Project Management Professional (PMP®) and a member of the PMI®-Honolulu Chapter.

Ken’s book — Project Management PRAXIS (available from Amazon) — includes many other innovative project management tools & techniques; and describes a “Toolkit” of related templates available directly from him at kenfsmith@aol.com.

To view other works by Ken Smith, visit his author showcase in the PM World Library at https://pmworldlibrary.net/authors/dr-kenneth-smith/


[1] Amade, B. (2020). A Computer Based Approach for Determining the Probability of Completing a Project at a Certain Due Date; PM World Journal, Vol. IX, Issue VI, June.

[2]Smith, K.F. (2019).  Estimating Realistic Activity Times: A Critical Pseudoscience Problem and Workaround Solution, PM World Journal, Vol. VIII, Issue IX, October.