introduction to pert and cpm also it include some examples

1. Network analysis
CPM/PERT
BLESSY V.A.

2. Project
A project is a series of activities directed to
accomplishment of a desired objective.
Network analysis
Network analysis is the general name given to
certain specific techniques which can be used for
the planning, management and control of projects

3. NETWORK TECHNIQUES
3
PERT CPM
-Project Evaluation and
Review Technique Critical Path Method
Gantt Chart also used in scheduling
Main difference is probabilistic and deterministic
in time estimation
Both use same calculations, almost similar

4. Activity : An arrow leads from tail to head directionally
–Indicate ACTIVITY, a time consuming effort that is required to
perform a part of the work.
Event : A node is represented by a circle
- Indicate EVENT, a point in time where one or more activities
start and/or finish.
Network :Combination of all project activities and the events
DEFINITION OF TERMS IN A NETWORK ANALYSIS

5. 5
ACTIVIT
Y
PRECEEDIN
G
SUCCESSO
R
EVENT

6. Three types of information are needed to
describe a project
1.Activity information: Break down the project into its
individual activities (at the desired level of detail).
2. Precedence relationships: Identify the immediate
predecessor(s) for each activity.
3. Time information: Estimate the duration of each
activity.

7. Types of project
networks
activity on arc (AOA) project network
where each activity is represented by an arc. A node is used to
separate an activity (an outgoing arc) from each of its immediate
predecessors (an incoming arc).
activity on node (AON) project network
where each activity is represented by a node. The arcs then are used
just to show the precedence relationships between the activities.

8. Network of Four Activities
8
1 3 4
2
A
B C
D
Arrows indicate project activities
Nodes correspond to the beginning
and ending of activities

9. CPM - Critical Path Method
Definition: In CPM activities are shown as a network of
precedence relationships using activity-on-node
network construction.
USED IN : Production management - for the jobs of
repetitive in nature where the activity time
estimates can be predicted with considerable
certainty due to the existence of past
experience.

10. Activity Slack
Each event has two important times associated with it :
- Earliest time , Te , which is a calendar time when a event can
occur when all the predecessor events completed at the
earliest possible times
- Latest time , TL , which is the latest time the event can occur
with out delaying the subsequent events and completion of
project.
• Difference between the latest time and the earliest time of an
event is the slack time for that event
Positive slack : Slack is the amount of time an event can be
delayed without delaying the project completion

11. 11
Activity, duration, ES, EF, LS, LF
2
3
C [5,9]
4 [8,12]
Activity
ES = earliest start time
EF = earliest finish time
LF = latest finish time
LS = latest start
time

12. Critical Path
• Is that the sequence of activities and events where
there is no “slack” i.e.. Zero slack
• Longest path through a network
• minimum project completion time

13. 13
• If can spend resources to speed up some activity, do
so only for critical activities.
• Don’t waste resources on non-critical activity, it will
not shorten the project time.
• If resources can be saved by lengthening some
activities, do so for non-critical activities, up to limit of
float.
Importance of Float (Slack) and Critical Path

14. Information's related to paddy
field
activity duration
1-2 Mat preparation 4
1-3 Land preparation 3
3-4 transplanting 3
4-5 Herbicide application 1
4-7 Weeding 4
4-6 Fertilizer application 1
7-8 harvesting 3

15. 15
1
3
4
2
5
7
6
8ES= 4
LF = 4
ES= 0
LF = 0
4
0
3 ES= 4
LF = 4
3
ES= 11
LF = 11
1
ES= 8
LF = 11
ES=8
LF = 11
ES= 7
LF = 7
ES= 14
LF = 14
0
0
1
4
Critical path length is 14 weeks in case of
paddy
3

16. In formations related to cowpea
activity duration
1-2 ploughing 2
1-3 Weeding 2
3-4 sowing 1
4-5 Irrigation 1
4-7 Plant protection 3
4-6 harvesting 4

17. 17
1
2
3
5
7
6
4
ES= 0
LF = 0
2 ES= 2
LF = 2
2
ES= 7
LF = 7
1
ES= 5
LF = 7
ES=7
LF = 7
ES= 4
LF = 4
ES= 10
LF = 10
0
0
3
1
3
Critical path length is 10 weeks in case of cowpea.

18. activity duration
1-2 Plant material preparation 2
1-3 Land preparation 2
3-4 planting 2
4-5 Irrigation 10
4-7 Fertilizer application 2
4-8 Pest management 15
4-6 weeding 16
8 -9 harvesting 4
Information's related to banana

19. 19
1
3
4
2
5
8
6
9ES= 2
LF =2
ES= 0
LF = 0
2
0
2 ES= 2
LF = 2
2
ES= 20
LF = 20
10
ES= 14
LF = 20
ES=20
LF = 20
ES= 4
LF = 4
ES= 24
LF = 24
0
16
15
Critical path length is 24 weeks in case
of BANANA
7
ES=6
LF=20
002 4

20. Information – tapioca
activity Duration
1-2 Land preparation 4
2-3 Planting 4
3-4 Weeding 15
3-6 Irrigation 8
3-5 Fertilizer 12
6-7 Irrigation 2
8-9 Inter cropping 6
9-10 Harvesting 3
6-8 Shoot removal 4

21. 21
1
2
3
4
6
5
8
ES= 0
LF = 0
4
ES= 2
LF = 2
ES= 23
LF = 23
0
ES= 23
LF = 23
ES=20
LF = 23
ES= 8
LF = 8
ES= 25
LF = 27
Critical path length is 36 weeks in case of tapioca.
7
9
10
4
15
8
12
2
ES= 27
LF = 27
4
0
ES= 33
LF = 33
ES= 36
LF = 36
3
6

22. “From the four networks we can conclude
that the minimum possible time to complete
the field operations is 36 weeks.”

23. PERT -
Project Evaluation & Review Techniques
Definition: In PERT activities are shown as a network
of precedence relationships using activity-on-arrow
network construction
USED IN : Project management - for non-
repetitive jobs (research and development
work), where the time and cost estimates
tend to be quite uncertain. This technique
uses probabilistic time estimates.

24. 24
PERT For Dealing With Uncertainty
• Use 3 time estimates
m= most likely time estimate, mode.
a = optimistic time estimate,
b = pessimistic time estimate, and
Expected Value (TE) = (a + 4m + b) /6
Variance (V) = ( ( b – a) / 6 )2
Std Deviation (δ) = SQRT (V)

25. 25
Precedences And Project Activity Times
Immediate Optimistic Most Likely Pessimistic EXP Var S.Dev
Activity Predecessor Time Time Time TE
V σ
a - 10 22 22 20 4 2
b - 20 20 20 20 0 0
c - 4 10 16 10 4 2
d a 2 14 32 15 25 5
e b,c 8 8 20 10 4 2
f b,c 8 14 20 14 4 2
g b,c 4 4 4 4 0 0
h c 2 12 16 11 5.4 2.32
I g,h 6 16 38 18 28.4 5.33
j d,e 2 8 14 8 4 2

26. Benefits of CPM/PERT
• Useful at many stages of project
management
• Mathematically simple
• Give critical path and slack time
• Provide project documentation
• Useful in monitoring costs

27. 1. Construction of a new plant
2. Research and development of a new product
3. NASA space exploration projects
4. Movie productions
5. Building a ship
6. Government-sponsored projects for developing a
new weapons system
7. Relocation of a major facility
8. Maintenance of a nuclear reactor
9. Installation of a management information system
10. Conducting an advertising campaign
Applications in the fields

28. Results of CPM & PERT
• Completion date
• About Schedule
• Within Budget
• Critical Activities
• How can the project be finished early at the least cost

29. Limitations to CPM/PERT
• Clearly defined, independent and stable
activities
• Specified precedence relationships
• Over emphasis on critical paths

30. Thank you