The Program Evaluation and Review Technique (PERT) is a statistical tool used in project management to analyze the tasks involved in completing a project. It involves defining tasks, organizing them into a network diagram, and estimating activity times and dependencies. This allows project managers to compute the minimum time needed to complete the project by identifying the critical path. PERT was developed for the U.S. Navy in the 1950s and facilitates decision making by making the dependencies and critical path of a project visible.

1. PROGRAM EVALUATION REVIEW TECHNIQUE
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2. VINCI VIVEKA
•A statistical tool, used in project management
• It is designed to analyze and represent the tasks
involved in completing a given project.
•A decision making tool designed to save time in
achieving end objectives.
•It is one of the techniques of scientific management.
•It was developed for the U.S. Navy Special Projects
Office in 1957 to support the U.S. Navy's Polaris
nuclear submarine project

3. PERT
PERT chart is a tool that facilitates decision making.
PERT is a method to analyze the involved tasks in completing
a given project, especially the time needed to complete each
task and to identify the minimum time needed to complete the
total project.
PERT is valuable to manage where multiple tasks are
occurring simultaneously to reduce idleness.
For this it takes into consideration three factors:
1. Time
2. Resources
3. Technical Performance Specifications.
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4. TERMINOLOGY
PERT Event: a point that marks the start or completion of one or
more activities. It consumes no time and uses no resources. When it
marks the completion of one or more tasks, it is not “reached” (does
not occur) until all of the activities leading to that event have been
completed.eg- start and finish*
Predecessor Event: an event that immediately precedes some other
event without any other events intervening. An event can have
multiple predecessor events and can be the predecessor of multiple
events. Eg: A and b are predecessor of C*
Successor Event: an event that immediately follows some other
event without any other intervening events. An event can have
multiple successor events and can be the successor of multiple
events.eg: D is the successor of C*.
*(refer Gantt Diagram)
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5. Optimistic Time (O): the minimum possible time required to
accomplish a task, assuming everything proceeds better than
is normally expected
Pessimistic Time (P): the maximum possible time
required to accomplish a task, assuming everything goes
wrong (but excluding major catastrophes).
Most Likely Time (M): the best estimate of the time
required to accomplish a task, assuming everything proceeds
as normal.
Expected 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 (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).
TE = (O + 4M + P) ÷ 6
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6. PERT Activity: the actual performance of a task which
consumes time and requires resources (such as
labor, materials, space, machinery). It can be understood as
representing the time, effort, and resources required to move
from one event to another. A PERT activity cannot be
performed until the predecessor event has occurred. Eg:
A,B,C,D*
Float or Slack is a measure of the excess time and
resources available to complete a task. It is the amount of time
that a project task can be delayed without causing a delay in
any subsequent tasks (free float) or the whole project (total
float). Positive slack would indicate ahead of schedule; negative
slack would indicate behind schedule; and zero slack would
indicate on schedule.
Critical Path: the longest possible continuous pathway taken
from the initial event to the terminal event. It determines the
total calendar time required for the project; and, therefore, any
time delays along the critical path will delay the reaching of the
terminal event by at least the same amount.
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7. Activity Predecessor Time Estimates Te
O M P
A - 2 8 6 4.00
B - 3 5 9 5.33
C A,B 4 5 7 5.17
D C 4 6 10 6.13
TE = (O + 4M + P) ÷ 6
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8. Gantt Chart
( According to the table in previous chart)
Activity On Node (AON) Diagram
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9. EARLY DURATION EARLY
START FINISH
A
LATE SLACK LATE
START FINISH
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10. In order to determine these following are the steps-
EARLY FINISH [ EF ]
Formula for EF= ES + Duration.
Duration can be taken from the table it is represented by Te
For the first activity i.e. START Early Start [ ES] =0,
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As start is a pert event its duration is zero.
Therefore, for START
ES=0 Duration =0 ; EF= ES + Duration => EF=0
EF of the predecessor event becomes ES of its successor.
Therefore, for A
ES=0 Duration=4, EF=4
For B,( as A&B both have same Predecessor i.e. START hence B----
ES=0 Duration= 5.33 EF=5.33
For C ( as A&B both are C predecessor hence we take the one with higher
value)
ES=5.33 Duration=5.17 EF=10.5

11. For D,
ES= 10.5 Duration=6.13 EF=16.63
For FINISH [as FINISH is a pert event its duration is zero]
ES=16.63 Duration=0 EF=16.63
LATE START [ LS ]
Formula LS=LF – DURATION
In this we start with FINISH, as it is the last activity. LATE FINISH [LF ] of
FINISH = its EF.
Therefore, LF=EF=16.63 Duration= 0 LS=LF- Duration , Hence LS=16.63
For D, [ LS of successor event becomes LF for its predecessor event ]
LF=16.63 Duration=6.13 LS=10.5
For C,
LF=10.5 Duration=5.17 LS=5.33
For B,
LF=5.33 Duration=5.33 LS= 0
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12. For A, [ as C is also its successor ]
LF=5.33 Duration=4 LS=1.33
For START [as A&B both are successor but we take here one with the lower
value ]
LF=1.33 Duration =0 LS=1.33
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SLACK
To determine the critical path we have to find whether any activity has a slack.
Activity on the critical path has slack zero.
Formula SLACK=LF-EF or SLACK= LS-ES
For START For C
LS=1.33 ES=0 SLACK=1.33 LS=5.33 ES=5.33 SLACK=0
For A For D
LS=1.33 ES=0 SLACK=1.33 LS= 10.5 ES=10.5 SLACK=0
For B For FINISH
LS=5.33 ES=0 SLACK=5.33 LS=1.33 ES=0 SLACK=1.33

13. ES=0 DUR=0 EF=0 ES=0 DUR=4 EF=4
START A
LS=1.33 SLACK=1.33 LF=1.33 LS=0 SLACK=1.33 LF=5.33
ES=0 DUR=5.33 EF=5.33 ES=5.33 DUR=5.17 EF=10.5
B C
LS=0 SLACK=5.33 LF=5.33 LS=5.33 SLACK=0 LF=10.5
ES=10.5 DUR=6.13 EF=16.33 ES=16.63 DUR=0 EF=16.63
D FINISH
LS=10.5 SLACK=0 LF=16.63 LS=16.63 SLACK=1.33 LF=16.63
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14. CRITICAL PATH
It is the longest continous -path way. There can be
more than one critical path or the path can change.
In the drawn Gantt diagram there are two
alternatives to reach FINISH and adding there
SLACK timing-
START+A+C+D+FINISH=3.99
START+B+C+D+FINISH=7.99
Hence , the path START+B+C+D+FINISH is the
longest it is the critical path, shown in the diagram
in the next slide.
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15. VINCI VIVEKA
CRITICAL PATH
[ in red ink ]

16. •PERT chart explicitly defines and makes visible
dependencies (precedence relationships) between the
work breakdown structure (commonly WBS) elements
•PERT facilitates identification of the critical path and
makes this visible
•PERT facilitates identification of early start, late start,
and slack for each activity
•PERT provides for potentially reduced project duration
due to better understanding of dependencies leading to
improved overlapping of activities and tasks where
feasible.
•The large amount of project data can be organized &
presented in diagram for use in decision making.
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17. DISADVANTAGES:
•There can be potentially hundreds or thousands of activities and
individual dependency relationships
•PERT is not easily scalable for smaller projects
•The network charts tend to be large and unwieldy requiring
several pages to print and requiring special size paper
•The lack of a timeframe on most PERT/CPM charts makes it
harder to show status although colours can help (e.g., specific
colour for completed nodes)
•When the PERT/CPM charts become unwieldy, they are no
longer used to manage the project.
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18. VINCI VIVEKA
Prepared by:
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M.ED SCHOLAR [2012-2013]
ST. XAVIER’S COLLEGE OF EDUCATION, PATNA.
vivekavinci@gmail.com
REFERENCE:
http://en.wikipedia.org/wiki/Program_Evaluation_and_Review_Technique