Tutorial 5 – Software Project Risk Management
Q1.
You are in charge of a software project. However, your company does not have a hazard
checklist or questionnaire. You decide to produce your own checklist. List at least one
question that you might include under each of the following categories. You may suggest
your own factor.
1.
2.
3.
4.
5.
6.
7.
Q2.
Application factors
Project factors
Hardware/Software factors
Changeover factors
Supplier factors
Environment factors
Health and safety factors
The following table shows the risk estimation of a project. Suggest the two most
important risk items that you would add. Estimate their likelihood and their impact.
Since you do not have enough resources to fix all the problems. Identify three most
important items that you need to attend to according to their risk exposure.
Id.
R1
R2
R3
R4
R5
R6
Q3.
Changes to requirements specifications
during coding
Specification takes longer than expected
Late hardware delivery
Module coding time longer than expected
Module testing demonstrates errors in
design
Staff sickness affecting critical path
activities
Likelihood
1
Impact
Risk
Exposure
8
3
5
1
4
7
7
3
5
9
9
Following is a list of top ten risks presented by Boehm in his Tutorial on Software Risk
Management. Suggest two or more risk reduction techniques for each risk. (Group
Discussion)
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
Q4.
Hazard
Personnel shortfalls
Unrealistic schedules and budgets
Developing the wrong software functions
Developing the wrong user interface
Gold plating
Continuing stream of requirements changes
Shortfalls in externally performed tasks
Shortfalls in external furnished components
Real-time performance shortfalls
Straining computer science capabilities.
Program Evaluation and Review Technique (PERT) is another common technique that
takes into accounts of risk in activity planning. PERT is developed to account for
uncertainties in the estimation of task duration. It is developed for the Fleet Ballistics
Missiles Program. It is similar to CPM. However, for each task in the activity plan,
PERT requires three time estimates instead of a single one in CPM. The three time
estimates are:
a.
b.
c.
Optimistic time (a) – the shortest time for an activity to be completed
Most likely time (m) – the time that we would expect the task to be finished
Pessimistic time (b) – the worst possible time for an activity to complete allowing for
all reasonable things to happen except for the ideal worst case scenario
In order to combine the effects of these three estimates, the expected time (t) and the
standard deviation (s) are calculated based on the following formula:
t = (a + 4*m + b)/6
s = (b – a)/6
and
Table 1 gives the PERT activity time estimates of a project and the corresponding PERT
diagram is given in Figure 1. Complete the table using the given formula and the figure
using the technique for CPM (forward pass and backward pass). [Hint: Use
s  s12  s22    sn2 to combine the effect of the standard deviations s1 , s 2 ,, s n
of the previous activities. If there are two different paths to a node, use the one with the
highest standard deviation.]
Table 1 The PERT activity time estimates
Task
Name
Id.
A
B
C
D
E
F
G
H
Percedent
Hardware selection
Software design
Hardware installation
Coding and testing
File take-on
Documentation
User training
System installation and testing
A
B
B
E, F
C, D
Optimistic
(a)
5
3
2
3.5
1
8
2
2
Duration Estimation
Most
Pessimistic Expected
likely (m)
(b)
(t)
6
8
6.17
4
5
4.00
3
3
2.83
4
5
4.08
3
4
10
15
3
4
2
2.5
Standard
dev. (s)
0.50
0.33
0.17
0.53
*Each node may have a target date.
These
targetPERT
datesactivity
are normally
set by external conditions. For
Figure
1 The
diagram
example, the project has to be finished in 15 weeks. The Activity C must be finished by week 11. The
staffs involved in Activity F are reassigned to other projects at week 10. Once the PERT activity
diagram is determined, you can estimate the probability for the node to be finished in time. See
Target date
C
Section 7.8 of Hughes book for detailed calculations.
t
=
2.83
2
s = 0.17
A
6.17
0.50
t = 6.17
s = 0.50
B
t = 4.00
s = 0.33
1
0
3
D
t = 4.08
s = 0.25
0
F
t=
s=
4
11*
9
0.53
E
t=
s=
G
t=
s=
5
10*
H
t = 2.08
s = 0.08
6
15*