2. Introduction
Program Evaluation and Review
Technique.
Analyze the tasks.
United States Navy.
Event-oriented Technique
Major Factor – Time
Ex: 1968 Winter Olympics in Grenoble
3. The main objective of PERT :
To facilitate decision making and
To reduce both the time and cost
required to complete a project.
Related Tools:
Critical Path Method.
Gantt chart
Applied to:
Very large-scale,
One-time,
Complex,
Non-routine infrastructure and
Research and Development projects
4. Planning Steps
Specific activities and milestones.
Sequence of the activities.
Network diagram.
Estimate the time.
Critical path.
Update the PERT chart.
5. What Happens
Identify the specific activities and
milestones
Activities.
Milestones.
It is helpful to list the tasks in a table.
6.
May be combined with the activity
identification step
Since the activity sequence is evident for
some tasks.
Other tasks may require more analysis
To determine the exact order in which they
must be performed.
7.
Activity sequence information
A network diagram can be drawn showing the
sequence of the serial and parallel activities.
Each activity represents: A node in the
network,
The arrows represent: The relation between
activities.
Software packages simplify this task
By automatically converting tabular activity
information into a network diagram.
8.
Weeks are a commonly used unit of time for
activity completion.
A distinguishing feature of PERT.
Its ability to deal with uncertainty in activity completion
time.
Optimistic time(O)
The shortest time in which the activity can be
completed.
To specify optimistic time to be three standards
deviations from the mean.
Most likely time(M)
The completion time having the highest probability.
9. Pessimistic time (P)
the maximum possible time required to accomplish a
task, assuming everything goes wrong (but excluding
major catastrophes).
PERT assumes a beta probability
distribution for the time estimates.
Estimated Time(TE)
The best estimate of the time required to
accomplish a task, accounting for the fact that
things don't always proceed as normal.
TE = (O + 4M + P) ÷ 6
10.
The critical path is
Determined by adding the times for the activities in
each sequence.
Determining the longest path in the project.
The critical path determines the total calendar
time required for the project.
If activities outside the critical path speed up or
slow down (within limits), the total project time
does not change.
The amount of time that a non – critical path
activity can be delayed without the project is
referred to as a slack time.
11. Critical Path is helpful to determine
ES – Earliest Start time
EF - Earliest Finish time
LS – Latest Start time
LF - Latest Finish time
The variance in the project completion time
can be calculated by summing the
variances in the completion times of the
activities in the critical path.
The project can be accelerated by adding
the resources required to decrease the time
for the activities in the critical path.
Shortening of the project sometimes is
referred to as Project Crashing.
12.
Make adjustments in the PERT chart as the
project progresses.
As the project unfolds, the estimated
times can be replaced with actual times.
In cases where
There are delays,
Additional resources may be needed to stay
on schedule
The PERT chart may be modified to reflect the
new situation.
13. Advantages
Explicitly defines and makes visible
dependencies between the WBS elements
Facilitates identification of the critical
path.
Facilitates identification of
Start date,
End date, and
Slack time for each activity,
Provides potentially reduced project
duration.
The large amount of project data can be
organized & presented in diagram for use
in decision making.
14. Disadvantages
Hundreds or thousands of activities and
individual dependency relationships
Not easily scalable for smaller projects
The network charts tend to be large and
unwieldy requiring several pages to print.
The lack of a timeframe on most charts
makes it harder to show status although
colours can help
When the charts become unwieldy, they
are no longer used to manage the project.
15. Case Study
In this Case Study, the Project
manager knows
The succession of the project
activities ,
Optimistic Time,
Pessimistic Time and
Most Likely Time
All the times known are in weeks.
-1-PERT was developed primarily to simplify the planning and scheduling of large and complex projects
-3- First developed by the United States Navy in 1950s.
-4-Event-oriented Technique rather than start- and completion-oriented.
The critical path method (CPM) is an algorithm for scheduling a set of project activities.
-1-Identify the specific activities and milestones.
-2-Determine the proper sequence of the activities.
-3-Construct a network diagram.
-4-Estimate the time required for each activity.
-5-Determine the critical path.
-6-Update the PERT chart as the project progresses.
-1-The activities are the tasks required to complete a project.
-2-The milestones are the events marking the beginning and the end of one or more activities.
-3-It is helpful to list the tasks in a table that in later steps can be expanded to include information on sequence and duration.
-1-Weeks are a commonly used unit of time for activity completion, any consistent unit of time can be used.
-3-2-So that there is a approximately a 1% chance that the activity will be completed within the optimistic time.
-4-Note that this time is different from the expected time.
The implication being that the expected time is the average time the task would require if the task were repeated on a number of occasions over an extended period of time.
-1-A work breakdown structure element may be a product, data, a service, or any combination
-4-Better understanding of dependencies leading to improved overlapping of activities and tasks were feasible.
