Project Planning & Scheduling – PM0011 Page 1 of 12 Master of Business Administration-MBA Semester 3 Project Planning & Scheduling – PM0011 Assignment Set - Q.1 Explain the following a. Rolling wave planning b. Decomposition c. Precedence diagramming method d. Dependency determination Ans: a. Rolling wave planning: this is a technique which plans as and when the project unfolds. In this technique the plans are made with the upcoming events. It is not often possible to foresee the future activities in a project with consistent detail over the entire period of the project. Therefore, planning is often done in "waves" or stages, with the activities in the near term planned in detail and the activities in the longer distance of time left for future detail planning. There may in fact be several planning waves, particularly if the precise approach or resource requirement is dependent or conditioned on the near-term activities. Such a planning approach is commonly called rolling wave planning. Rolling Wave Characteristics The fact is that the distinguishing characteristic of the planning done now for a future wave is that both cost accounts and network tasks are "long" (or "large") compared to their near-term counterparts. We have already discussed the long task in this discussion. Project managers can substitute the words "large cost account" for "long task" and all of the statistical discussions apply, except that the principles and techniques are applied to the cost accounts on the WBS and not to the network schedule. Monte Carlo Effects in the Rolling Wave Whether you are doing a Monte Carlo analysis on the WBS cost or on the network schedule, the longer tasks and larger work packages have greater variances. The summation of the schedule at its outcome milestone or the summation of the WBS cost at the top of the WBS will be a normal distributed outcome regardless of the rolling waves. However, the Monte Carlo simulation will show you what you intuitively know: the longer task and larger cost accounts, with their comparatively larger variances, will increase the standard deviation of the Normal distribution, flatten its curve, and stretch its tails. As the subsequent waves come and more details are added, the overall variances will decrease and the Normal distribution of the outcome variable, whether cost or schedule, will become more sharply defined, the tails will be less extreme, and the standard deviation (which provides the project manager entrée to the confidence tables) will be more meaningful. The Critical Chain There is a body of knowledge in schedule and resource planning that has grown since 1997 when Eliyahu M. Goldratt wrote Critical Chain,* arguably one of the most significant books in project management. In this book, written like a novel rather than a textbook, Goldratt applies to project management some business theories he developed earlier for managing in a production operation or manufacturing environment. Those theories are collectively called the Theory of Constraints. As applied to project management, Goldratt asserts that the problem in modern project management is ineffective management of the critical path, because the resources necessary to ensure a successful critical path are unwittingly or deliberately scattered and hidden in the project. The Theory of Constraints In the Theory of Constraints, described in another Goldratt business novel, The Goal,** the idea put forward is that in any systemic chain of operations, there is always one operation that constrains or limits the throughput of the entire chain. Throughput is generally thought of as the value-add product produced by the operation that has value to the customer. If the chain of operations is stable and not subject to too many random errors, then the constraint is stable and identifiable; in other words, the constraint is not situational and does not move around from one job session, batch, or run to the next. 1
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Project Planning & Scheduling – PM0011 Page 1 of 12
Master of Business Administration-MBA Semester 3
Project Planning & Scheduling – PM0011
Assignment Set-
Q.1 Explain the following
a. Rolling wave planning b. Decomposition
c. Precedence diagramming method d. Dependency determination
Ans:
a. Rolling wave planning: this is a technique which plans as and when the project unfolds. In this
technique the plans are made with the upcoming events.
It is not often possible to foresee the future activities in a project with consistent detail over the
entire period of the project. Therefore, planning is often done in "waves" or stages, with the
activities in the near term planned in detail and the activities in the longer distance of time left
for future detail planning. There may in fact be several planning waves, particularly if the precise
approach or resource requirement is dependent or conditioned on the near-term activities. Such
a planning approach is commonly called rolling wave planning.
Rolling Wave Characteristics
The fact is that the distinguishing characteristic of the planning done now for a future wave is
that both cost accounts and network tasks are "long" (or "large") compared to their near-term
counterparts. We have already discussed the long task in this discussion. Project managers can
substitute the words "large cost account" for "long task" and all of the statistical discussions apply,
except that the principles and techniques are applied to the cost accounts on the WBS and not
to the network schedule.
Monte Carlo Effects in the Rolling Wave
Whether you are doing a Monte Carlo analysis on the WBS cost or on the network schedule, the
longer tasks and larger work packages have greater variances. The summation of the schedule
at its outcome milestone or the summation of the WBS cost at the top of the WBS will be a normal
distributed outcome regardless of the rolling waves. However, the Monte Carlo simulation will
show you what you intuitively know: the longer task and larger cost accounts, with their
comparatively larger variances, will increase the standard deviation of the Normal distribution,
flatten its curve, and stretch its tails.
As the subsequent waves come and more details are added, the overall variances will decrease
and the Normal distribution of the outcome variable, whether cost or schedule, will become
more sharply defined, the tails will be less extreme, and the standard deviation (which provides
the project manager entrée to the confidence tables) will be more meaningful.
The Critical Chain
There is a body of knowledge in schedule and resource planning that has grown since 1997
when Eliyahu M. Goldratt wrote Critical Chain,* arguably one of the most significant books in
project management. In this book, written like a novel rather than a textbook, Goldratt applies to
project management some business theories he developed earlier for managing in a production
operation or manufacturing environment. Those theories are collectively called the Theory of
Constraints. As applied to project management, Goldratt asserts that the problem in modern
project management is ineffective management of the critical path, because the resources
necessary to ensure a successful critical path are unwittingly or deliberately scattered and
hidden in the project.
The Theory of Constraints
In the Theory of Constraints, described in another Goldratt business novel, The Goal,** the idea
put forward is that in any systemic chain of operations, there is always one operation that
constrains or limits the throughput of the entire chain. Throughput is generally thought of as the
value-add product produced by the operation that has value to the customer. If the chain of
operations is stable and not subject to too many random errors, then the constraint is stable and
identifiable; in other words, the constraint is not situational and does not move around from one
job session, batch, or run to the next.
1
Project Planning & Scheduling – PM0011 Page 2 of 12
To optimise the operation, Goldratt recommends that if the capacity of the constraint cannot be
increased, or the constraint cannot be removed by process redesign, then all activities ahead of
the constraint should be operated in such a manner that the constraint is never starved. Also,
activities ahead of the constraint should never work harder, faster, or more productively than the
minimum necessary to keep the constraint from being starved. Some may recognise this latter
point as a plank from the "just-in-time" supply chain mantra, and in fact that is not a bad way to
look at it, but Goldratt's main point was to identify and manage the constraint optimally.
From Theory of Constraints to Critical Chain
When Goldratt carried his ideas to project management, he identified the project constraint as
the critical path. By this association, what Goldratt means is that the project is constrained to a
certain duration, and that constrained duration cannot be made shorter. The consequence of
the critical path is that constrained throughput (valuable deliverables to the project sponsor)
cannot be increased, and indeed throughput is endangered if the critical path cannot be
properly managed.
Goldratt made several recommendations in his book Critical Chain, but the most prominent are:
The tasks on the critical path do indeed require statistical distributions to estimate the range
of pessimism to optimism. But, unlike PERT or CPM, Goldratt insists that the median value, the
50% confidence level, be used. Using the median value, the so-called 50-50 point, means
that there is equal likelihood that the task will underrun as overrun. (PERT uses the BETA
distribution and requires that the expected value be used. CPM traditionally uses a single-
point estimate and, more often than not, the single estimate used is the "most likely" outcome
and not the expected value.)
All task activity in the project schedule network that is not on the critical path should be
made subordinate to the demands of the critical path.
There should be "buffers" built into any path that joins the critical path. A buffer is a task of
nonzero duration but has no performance requirement. In effect, buffer is another word for
reserve. However, Goldratt recommends that these buffers be deliberately planned into the
project.
By using the median figure for each task on the critical path, Goldratt recognises that the
median figure is generally more optimistic than the CPM most likely estimate and is often
more optimistic than the expected value. Goldratt recommends that the project manager
"gather up" the excess pessimism and put it all into a "project buffer" at the end of the
network schedule to protect the critical path.
We have already discussed Goldratt's point about a project buffer in our earlier discussion
about how to represent the project schedule risk as calculated on the network with the
project sponsor's business value dates as set in the programme milestones. We did not call it
a buffer in that discussion, but for all intents and purposes, that is what it is. Figure 7-15
illustrates the placement of buffers in critical chain planning.
The critical chain ideas are somewhat controversial in the project management community,
though there is no lack of derivative texts, papers, projects with lessons learned, and
practitioners that are critical chain promoters. The controversy arises out of the following
points:
Can project teams really be trained to estimate with the median value? If so, then the critical
chain by Goldratt's description can be established.
Can team leaders set up schedule buffers by taking away schedule "pad" from cost account
managers, or does the concept of buffers simply lead to "pad" on top of "pad?" To the extent
that all cost account managers and team leaders will manage to the same set of principles,
the critical chain can be established.
Project Planning & Scheduling – PM0011 Page 3 of 12
b. Decomposition: this technique is about breaking project work packages into smaller more easily
manageable units.
Most projects important enough to have a significant impact on quality are too large to tackle
all at once. Instead, large projects must be broken down into smaller projects and, in turn, into
specific work elements and tasks. The process of going from project objectives to tasks is called
decomposition. Project decomposition begins with the preparation of a preliminary plan. A
preliminary project plan will identify, in broad high-level terms, the objectives of the project and
constraints in term of time and resources. The work to be performed should be described and
precedence relationships should be sketched out. Preliminary budgets and schedules will be
developed. Finally, subplans will be developed for each subproject for the following:
Control plans.
Quality control plans.
Cost control plans.
Schedule control plans.
Staffing plans.
Material plans.
Reporting plans.
Other plans as deemed necessary.
These subplans are developed in parallel for the various subprojects.
Improvement happens one project at a time, but without proper planning these project may
well fail to deliver their objectives.
c. Precedence Diagramming Method (PDM): is a method for constructing project schedule network
diagram that has rectangular boxes, depicting nodes and arrows connecting the boxes,
depicting the logical relationship between the activities. this technique is also called Activity on
Node (AON).
Fig. 1: Activity on Node
d. Dependency determination: this technique is used to define the sequence based on the types of
dependencies between the activities.
Q.2 State and describe process of estimating resource & duration for the activity
Ans: As we are already aware that for every step we take has a time frame and every move needs
some resource and both these parameters need to be considered before each action. Thus even
though the activity is identified and sequenced, we get only partial schedule, to get further clarity
on the schedule it is very important to understand the resource requirement and time required to
complete each activity. The importance of the two parameters can be understood from the fact,
that project management has two separate processes for find the two requirements. The two
processes are:
· Determining resource requirement for each activity
· Calculating the time required for each activity
Determining resource requirement for each activity
There are various resources used on a project. Some of which are people, machinery, money. And
for each activity, to be accomplished we have a particular resource requirement. The reason for
calculating this requirement is, that there is a cost factor attached to each resource and to execute
the project successfully, it is very important that we are aware of the cost component.
The information or input to this process may be similar or different from the previous processes. The
basic inputs to this process are:
· List of activity
· Activity Characteristics
· Resource Calendar: this document gives us an idea of the resource availability for the project
activities. It also gives information about the resource skillset.