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CHAPTER 3.3

ESTIMATING TASK DURATIONS

A n entire chapter devoted to a discussion on the duration of tasks? He has to be
kidding, you say to yourself. But wait! Don’t move on to the next chapter just
yet. Think a bit about the relative importance of task durations. A project schedule is
the result of the aggregation of all the task durations. If the durations lack validity, so
does the project schedule. Fidelity in task duration estimating is essential to the de-
velopment of a wholesome project schedule. And such fidelity can only be achieved
via a structured and consistent approach toward establishing task durations.

How Long Does It Take to Catch a Fish?
Here’s a good question. How long does it take to catch a fish? Ridiculous, you
say. One can’t estimate the time to catch a fish. It could be just after you cast a
line in the water. It might be never. Or anywhere in between. As ridiculous as
this sounds, that is just the feeling that goes through our minds when we are
asked to estimate the duration for a task. Our first thought is How the h__
should I know? But we can’t get away with this. So we dig in and take a scientific
stab at the task duration.

First, we come up with a most likely estimate of the duration. This is the time
that we feel it would take about 50 percent of the times that we were to execute
the task. But we’re not comfortable with a 50 percent confidence factor. So we
add some time that we feel we could support about 90 percent of the time.

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