6^th    Installment: Don’t chisel first estimates into stone

  “It is a bad plan that admits of no modification”  – Publilius Syrus (1st century BC)

“I have not failed, I’ve just found 10,000 ways that won’t work.” – Thomas Alva Edison (1847-1931)

“There is no dishonor in rethinking a problem”  -Royal Bank of Canada Monthly Letter

When preliminary schedules are first developed, we all make SWAGs (Sciencetific Wildly Aspirating Guesses) on a projects work-breakdown structures or durations.

These estimate will rarely be accurate, because at the beginning of a project, our estimates are based on fuzzy requirement, they suffer from a lack of our experience doing similar work or from an uncertainty of what to do after the initial steps.   

That’s why it’s important to have some contingency time built into every project. The amount depends on the uncertainty of the project.  I’ve been on projects that needed a lot of contingency time built into the schedule because they tackled problems that had never been done before, such as building a deep space probe to Saturn that has a narrow launch window. 

I’ve also supported the scheduling group for the construction of a major military facility, where there was very little uncertainity in the project.   When the schedulers got to a task such as building a warehouse of a certain size they’d pull out their reference books and look up the days for construction, the amount of contingency appropriate for that construction.  Then, from other reference books, they’d figure in the lead time to order and ship materials. Then depending on the method of shipment, they’d compute how much extra to order to handle five finger discounts.  There wasn’t much need for contingency on that project.

For projects with high uncertainity, As the requirements of the project are clarified and understood, the Project Manager must make corrections to the original assumptions.  But how many  times have you heard the query from higher up in an organization “But you said in the original schedule that it should take “n” days to do that? “   That is the reason that you have to set up a workable process to correct the schedules.  Each honest iteration of a schedule will produce a more accurate estimate.   The Project Manager has to regularily remind management the the detail schedule is only good up to the uncertainity horizon of the project. (More on that topic later)

As stated in an earlier installment of this blog,  the Project Manager has to establish an environment in which the staff is not afraid to tell the truth.  This applies when correcting or updating the schedule.  It is the process of  honestly updating and statusing  the schedule that gives the manager insight into the project’s status.  The Project Manager’s response to problems which arise will determine how successful the rest of the project will be.  The Project manager must establish an environment in which people are willing to share all problems before they become unmanageable. 

I’ll be back in a few weeks with more.  Remember that the cleanliness of theory is no match for the clutter of reality.

 Best Regards,

Michael Hughes