Page 113 - Untitled-1

92 CRITICAL PATH, CRITICAL CHAIN, UNCERTAINTY

allow for tasks to exceed their most likely duration. So the concept of including
contingency is entirely defendable. But to counteract Parkinson, that contingency
is best left out of the individual tasks and placed in a shared buffer or dummy task.

It has also been my experience that schedule slippage often occurs between
tasks rather than within a task. Hence, placing the contingency in a shared buffer
allows for this phenomenon.

The other popular theory inherent in the various shared contingency methods
is that task durations are more realistic if they allow for 50 percent probability
rather than 90 percent probability. The time allowance of the risk that is taken out
of the individual tasks goes into the buffers.

Regardless of the disagreement on the various methods, there appears to be
consensus on the above issues.

Using Your Options

The bottom line here is to be aware that there are several options available to
plan and track project activity. There will be times when applying techniques such
as CCPM or PERT for planning projects will provide a better plan. Risk manage-
ment and contingency planning is always justified (not an option). Tracking op-
tions include percent complete, remaining duration, earned value, milestone
tracking, critical path tracking, and buffer analysis. I could never say that just one
of these is very important and that the others should be subordinated or ignored.
Each of these has its purpose.

The concept of shared contingency is one that I can highly support, but there
are many ways to do this. The critical chain theory has done much to bring the
concept of shared contingency, leaner task durations, and risk awareness to the
forefront. We can all learn from it and seek ways to address these issues.

Project success is not as dependent on the planning and control methods and
tools as it is on the behavior of managers and other personnel involved with con-
tributing to project performance. It has been well-documented that traditional
methods and tools tend to be intimidating to such personnel. Some claim that
CCPM lowers this barrier. I’m not sure that this is true. I am certain, however,
that improvement in the way that humans operate in the projects environment,
and their commitment to good planning and communication, and then execution
according to the plan, are the real keys to project success.