Activity Network Diagram
Brian McAluney
OISM 470W
PowerPoint Training Presentation
Overview
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Definition of an Activity Network Diagram
History
Basic Terms
How can it be used in your organization?
How the diagram works
Example
Activity Network Diagram Exercise
Summary
Definition of an
Activity Network Diagram
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Also known as the Program Evaluation
Review Technique (PERT) or Critical Path
Diagram
Tool used to control the length of projects
Takes into account many aspects of
projects: task times, slack times, critical
tasks, etc.
Definition of an
Activity Network Diagram (cont.)
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Designed for research and developmenttype projects
Determines a probability distribution for a
project
History
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Developed by the U.S. Department of
Defense
First used as a management tool for
military projects
Adapted as an educational tool for
business managers
Basic Terms
Basic Vocabulary of the PERT Diagram:
• Activity – part of the project represented by an
arrow or line
• Best Estimate(B) – earliest completion time
• Critical path(CP) – the most time consuming path
through the diagram with no slack time
• Earliest Start Time(EST) – earliest possible time
for an activity to begin
• Network – the project shown graphically
• Most likely estimate(M) – length of time probably
needed
Basic Terms (cont.)
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Expected Time(ET) – the average duration time
Event – represents the start or finish of one or
more events (shown as a circle, square, or other
symbol)
Latest Start Time(LST) – latest time an activity can
begin and still be completed before the next
activity
Slack Time – latest start time minus earliest start
time for an activity
Worst estimate(W) – pessimistic time estimate
How can it be used in your
organization?
Brainstorm ideas of where activity
network diagrams could be utilized
in your business practices…
How can it be used in your
organization?
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Finding minimum
completion times
Determining
maximum completion
times
Value of time for each
step in the project
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Assigning specified
times for parts of the
project
Creates a realistic
schedule for the
company
How the diagram works
Basic Rules:
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All preceding activities must be
completed before the project can begin
The arrows represent the logical
precedence of the project
How the Diagram Works (Cont.)
Procedure for development:
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Identify all activities and relationships among
them
Sketch the diagram
Estimate the times for each activity, or node, in
the diagram
Determine the critical path
Evaluate the diagram for milestones and target
dates in the overall project
Example
Activity Network Diagram
A
D
C
B
F
E
Exercise
Given the following formula, data, and
diagram, determine the critical path and
the expected time of the project.
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Time is represented in days
ET = 4(M) + 1(B) + 1(W) / 6
A = 2, B = 3, C = 1, D = 4, E = 3, F = 2, G = 2, H = 1,
and I = 3
Exercise (cont.)
A
D
C
B
G
F
E
I
H
Begin the Analysis
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Remember your steps
for PERT diagrams:
Using the given
diagram, list all the
steps
Determine task times
Determine
relationships
between the tasks
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Find the earliest start
time
Find the latest start
time
Determine slack and
the critical path
Summary
Review the exercise
 Advantages of PERT
 Disadvantages of PERT
 Odds and Ends
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Review the Exercise
 Did you arrive at the correct
answer?
 Do these answers make sense?
Advantages of PERT Diagrams
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Projecting plans before they begin
Helps to separate planning and scheduling
functions of a project
Controls projects
Clarifies maintenance of the plan
Shows dependency of different aspects of
the project
Advantages of PERT Diagrams
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Allows for concentration on the steps
themselves and not the time required for
each
Represents a realistic schedule
Focuses attention on critical aspects of the
plan
Changes can be made easily in the project
Disadvantages of PERT Diagrams
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Cannot handle all specific problems that
arise in each step of the project
Different graphical representations can be
made easier in other types of control
processes
Odds and Ends
Activity Network Diagrams have many more
advantages than disadvantages
 They are used in all types of businesses
 The topics that were covered should act as
the key in helping you lead your company
in their next business project
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Works Cited
Bedworth, David D. and James E. Bailey.
Integrated Production Control Systems. New
York: John Wiley & Sons, 1987.
“PERT”. Internet.
http://www.uwf.edu/coehelp/studentaccount
s/rnew/perthome.html. 12 February 2001.
Stamatis, D.H. TQM Engineering Handbook. New
York: Marcel Decker, Inc. , 1997.