The rest of the 'Unwritten Laws of Engineering' section on making estimates

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This is excerpted from: http://rotorlab.tamu.edu/me489_SP11/README/2010%20ASME%20Unwritten_Laws_of_Enginering.pdf


Promises, schedules, and estimates are necessary and important instruments in a well-ordered business.

Many engineers try to dodge making commitments. You must make promises based upon your best estimates
for your part of the job, together with estimates obtained from contributing departments for theirs. No one
should be allowed to avoid the issue by saying, “I can’t give a promise because it depends upon so many
uncertain factors.” Of course it does. You must account for them, estimating best and worse cases, and then
provide neither laughably padded nor unrealistically optimistic schedules. Both extremes are bad; good
engineers will set schedules that they can meet by energetic effort at a pace commensurate with the
significance of the job.

A corollary to this law is that you have a right to insist upon reasonable estimates from other departments. But
in accepting promises from other departments, make sure that you are dealing with a properly qualified
representative. Bear in mind that if you ignore or discount other engineers’ promises you dismiss their
responsibility and incur the extra liability yourself. Ideally, other engineers’ promises should be negotiable
instruments in compiling estimates.

Dorothy Kangas, a business process improvement specialist for The Nielsen Co., said that despite the many 
tools and techniques available for managing a project, sound estimating of resources and schedules is
fundamentally important: “Getting reliable estimates is key to creating and maintaining a project schedule.”
Kangas, who contributed to the Project Management Institute’s A Guide to the Project Management Body of
Knowledge, has seen both extremes: “Engineers or project team members sometimes provide estimates based
on the assumption that every task will be executed on time; that nobody goes on vacation, nobody is sick, and
absolutely no other factors interfere with the scheduled activities. I’ve seen others try to pad every one of
their tasks. Suddenly what seemed to be a realistic product development project will take twice as long as
expected.” But Kangas noted this as well: “A good project manager probably knows which engineers are
pessimistic and which are optimistic and tries to work the middle!”

One area that is often overlooked in planning projects, according to Kangas, is risk. “If there are uncertain
factors, or risks, those should be compiled and managed according to their impact and likelihood of actually
occurring,” she said.

Furthermore, according to Kangas, project risks and project issues are two different things; risks can be
predicted and managed, whereas issues arise unpredictably throughout a project. So risk management
activities should be scheduled into a project right from the start, but issues must be squeezed onto the
schedule as they appear.