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What should we do with unknowns in schedule risk?

How to identify and address known unknowns, unknown unknowns and unknown knowns – potentially the most important risks of all

10 August 2015 – New in the Library – “What should we do with unknowns in schedule risk?” is a new paper by Dr. David Hulett, one of the world’s leading authorities on project schedule risk management. This important new paper was published in the July edition of the PM World Journal and added to the PM World Library this month.

According to Dr. Hulett’s introduction, “Schedule risk analysis explores how unknowns applied to the project schedules may derive a distribution of possible completion dates. Unknowns include: known unknowns… unknown unknowns…and unknown knowns… This paper describes the types of unknowns and the methods used to incorporate the unknowns to drive the Monte Carlo simulation of the schedule. Methods include: (1) using the 3-point estimate to represent inherent variability, estimating error and estimating bias, (2) expanding the 3-point range for “far future” (in the context of the project) activities for unknown unknowns, and (3) using the risk interview to uncover unknown knowns, and. A simple case study shows, through use of Monte Carlo simulation, examples of the methods and of their impact on final answers.”

140609 - PMWL Logo for NitL - 125To read this paper, go to and click on the title. Access is free.