Some Useful Ideas
On Work Breakdown Structures
Some people ask: Why bother with a Work Breakdown Structure (WBS)? Joseph Heagney
answers that question as follows:
"A major problem in project planning is determining how long tasks
will take and what it will cost to do them. Inaccurate estimates are a leading
cause of project failures, and missed cost targets are a common cause of stress
and recrimination in project management.
The most useful tool for accomplishing all of these tasks is the WBS. The idea
behind the WBS is simple: You can subdivide a complicated task into smaller tasks
until you reach a level that cannot be further subdivided. At that point, it is
usually easier to estimate how long the small task will take and how much it will
cost to perform than it would have been to estimate these factors at higher levels."
Later, Joseph goes on:
"Generally, we use average times to plan projects... . That is
the idea, anyway [but] Parkinson's Law discredits this notion, however. Parkinson
said that work expands to fill the time allowed. That means that tasks may take
longer than the estimated time, but they almost never take less. One reason is
that when people find themselves with some time left, they tend to refine what
they have done. Another is that if they turn in work early, they may be expected
to do work faster the next time or that they may be given more work to do."
So it is important to recognize these realities when estimating and managing
your project. Joseph suggests
"Some guidelines for documenting estimates:
- Show the percent tolerance that is likely to apply.
- Tell how the estimate was made and what assumptions were used.
- Specify any factors that might affect the validity of the estimate (such as
whether the estimate will still be valid in six months).
In fact, it is impossible to make sense of any estimate unless these steps are
taken, so they should be standard practice."
On scope changes and multitasking
Joseph Heagney notes that:
"I am often told that scope and priorities change so often in a given
organization that it doesn't make sense to spend time finding critical paths [in
scheduling]. There are two points worth considering here. One is that if scope
is changing often in a project, not enough time is being spent doing upfront definition
and planning. Scope changes most often occur because something is forgotten. Better
attention to what is being done in the beginning usually reduces scope creep.
Second, if priorities are changing often, management does not have its act together.
Generally, the organization is trying to tackle too much work for the number of
resources available... . One company found, as an example, that when it stopped
having people work on multiple projects, employees' productivity doubled! That
obviously is highly significant."
On task durations
"A good rule of thumb to follow is that no task should have a duration
much greater than four to six weeks. For knowledge work, durations should be in
the range of one to three weeks, because knowledge work is harder to track than
One thing that caught our eye is Joseph's observation: "You Can't Have It All!"
and goes on to explain:
"One of the common causes of project failures is that the project
sponsor demands the project manager must finish the job by a certain time, within
budget, and at a given magnitude or scope, while achieving specific performance
levels. In other words, the sponsor dictates all four of the project constraints.
This doesn't work."
We agree, even though we are not entirely sure of the meaning of "Performance".
It could be the efficiency of the work performed by the project team, the quality
of the work reflected in the product, or the performance of the product in use
in successfully producing benefits? Nevertheless, the author expresses the relationship
mathematically as follows:
That is to say, "Cost is a function of Performance, Time, and Scope"
where function "f" is some factor or other.
Expressing this relationship mathematically is a useful idea. However, the
true project management variables are Scope (of the required product), Quality
(grade of the required product) as inputs that result in Time (required to do
the work) and the consequential Cost (of the whole exercise including materials,
equipment and overheads). Or as an equation:
Where "ƒ" is a factor reflecting the efficiency of the work force, its management
and the obstacles (risk events) encountered. But what this equation means is that
the author's relationship can be more precisely written as:
Obviously "ƒ" could be analyzed further but the problem is in determining
suitable cost scales for the S, Q, and T variables. Perhaps here is a valuable
area for future project management research, especially beneficial for estimating.
But simply understanding this relationship is a valuable background to decision-making.
15. Ibid, p75
16. Ibid, p77-78
17. Ibid, pp86-87
18. Ibid, p89
19. Ibid, p8