Often, estimates are initially made with an incomplete understanding of
requirements. Estimation is done at the beginning of the lifecycle before the
requirements are defined and thus the problem understood.
How can you accurately estimate unless you know what the problem we intend to
solve? At this point, they often represent wishes rather than realistic
estimates. As the project progresses and the problem become better
understood, estimates should be revisited. For example, NASA advocates re-
estimation at defined points in the lifecycle. Often, a Project Manager will
know that they should revise their estimates as they get a better
understanding of the requirements, but are afraid to; they feel they will be
viewed as a failure. A Project manager needs to be honest to themselves,
their team and stakeholders.
It is important that the Project Manager is not coaxed in... (more)