3. WBS VG System Development (Example)
7
1. VG System
1.1 VG Init 1.2 VG IO 1.3 VG RO 1.4 VG SRO
Work
Package
Population of
the screen for
the Service
No, and Data
Entry of
Primary &
Secondary
Activities
Population of
the screen for
the Service
No, and Data
Entry of
Comment &
Rating of
Primary &
Secondary
Activities
Population of
the screen for
the Service
No, and Data
Entry of
Comment ,
Rating &
Approval/
Rejection of
Primary &
Secondary
Activities
Population of
the screen for
the Service
No, and Data
Entry of
Comment ,
Rating &
Approval/
Rejection of
Primary &
Secondary
Activities
4. Activity Listing VG System (Example)
ID Activity Name Activity Description
1 Design Documentation Document the High level & Low level Design
2 Develop & Test VG Init Screen Develop & Test the Screen Population based on the Service No;
Addition Screen, & Modification Screen of Primary & Secondary
Activities
3 Develop & Test VG IO Screen Develop & Test the Screen Population all subordinate VG based
on the Service No; Addition Screen, & Modification Screen for
entering Comment, and Rating Primary & Secondary Activities
4 Develop & Test VG RO & SRO
Screen
Develop & Test the Screen Population all subordinate VG based
on the Service No; Addition Screen, & Modification Screen for
entering Comment, Rating and Approval/ Rejection of Primary &
Secondary Activities
5 Develop & Test VG System
Admin Module
Develop the Master Data Entry Screen, User Authentication
Screen
6 Integration Integration of all the modules
7 Integration Testing Integrated Functionality Testing,
8 System Testing System Performance Testing (Load & Stress Testing)..etc
9 Acceptance Testing Customer Validation of Deliverable
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12. more unusual links and relationships
so far all links have been finish-start links...
Task A Task B
Task A
Task C
Task C
Task A
Task B depends upon Task A, but
with a 3 day delay; B cannot start
until 3 days after A is finished
The finish of Task C depends
upon the finish of Task A
The start of Task C depends on
the start of Task A; this is a
start-to-start link; it may also
incorporate a delay
3 days
13. using the outputs
Gantt Charts
resource histograms
resource smoothing
optimising the schedule
14. Scheduling
task 1
task 2
task 3
task 4
task 5
task 6
task 7
task res. Duration Calendar
2 days
3 days
1 day
2 days
7 days
4 days
1 day
Jane
Bill
Jane
Jim
Bill
Jane
Bill
15. PERT and uncertainty - 1
Task 01
Task 02
Task 03
Task 04
4
2
5
4
The critical path looks
like tasks 01-02-04
But what if you are not
sure about the duration
for Task 03?
16. PERT and uncertainty - 2
Task 01
Task 02
Task 03
Task 04
4
2
5
4
The better estimate for
Task 03 might be its
PERT estimate, or
Expected Value, EV)
EV = O + 4L + P
_________
6
O = Optimistic estimate (say 2)
L = Most Likely (say 4)
P = Pessimistic (say 12)
In this example the EV = 6, which does, in fact
change the critical path
17. PERT and uncertainty - 3
But how confident can we be in these results?
An duration’s spread is the degree to which
estimates of the duration differ from each other.
If every estimate of duration were about equal,
the estimate would have very little spread.
There are many measures of spread. The
distributions on this page have the same mean but
differ in spread: the distribution on the bottom is
more spread out.
18. PERT and uncertainty - 4
Standard deviation is used as a measure of spread. In a normal
distribution, about 68% of estimates are within one standard
deviation of the mean and about 95% of the estimates are within
two standards deviations of the mean.
EV = O + 4L + P
___________
6
O = Optimistic estimate (say 2)
L = Most Likely (say 4)
P = Pessimistic (say 12)
SD = (P – O)/6 In our example SD = (12-2)/6 = 1.666
So, we could say that, for task 03:
With 68% certainty, the duration will be between 2.34 and 5.66 (4 ± SD)
With 95% certainty the duration will be between 0.68 and 7.32 (4 ± 2SD)