Chapter05

Supplementary Slides for
Software Engineering:
A Practitioner's Approach, 5/
e
copyright © 1996, 2001
R.S. Pressman & Associates, Inc.

For University Use Only
May be reproduced ONLY for student use at the university level
when used in conjunction with Software Engineering: A Practitioner's Approach.
Any other reproduction or use is expressly prohibited.

This presentation, slides, or hardcopy may NOT be used for
short courses, industry seminars, or consulting purposes.

These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,
5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001
1

Chapter 5
Software Project
Planning

2

Software Project
Planning
The overall goal of project
planning is to establish a
pragmatic strategy for controlling,
tracking, and monitoring a
complex technical project.

Why?

So the end result gets done on
time, with quality!

3

The Steps
t Scoping—understand the problem and
the work that must be done
t Estimation—how much effort? how
much time?
t Risk—what can go wrong? how can we
avoid it? what can we do about it?
t Schedule—how do we allocate
resources along the timeline? what are
the milestones?
t Control strategy—how do we control
quality? how do we control change?
4

Write it
Down!
Project Scope Software
Estimates Project
Risks Plan
Schedule
Control strategy

5

To Understand Scope ...
t Understand the customers needs
t understand the business context
t understand the project boundaries
t understand the customer’s motivation
t understand the likely paths for change
t understand that ...

Even when you understand,
nothing is guaranteed!

6

Cost Estimation

project scope must be explicitly
defined
task and/or functional
decomposition is necessary
historical measures (metrics) are
very helpful
at least two different techniques
should be used
remember that uncertainty is
inherent

7

Estimation Techniques
t past (similar) project experience
t conventional estimation techniques
¶ task breakdown and effort estimates
¶ size (e.g., FP) estimates
t tools (e.g., Checkpoint)

8

Functional Decomposition

Stateme functional
perform
of Scope
nt a decomposition
"grammatical
parse"

9

Creating a Task Matrix
Obtained from “process framework”

framework activities

application Effort required to
functions accomplish
each framework
activity for each
application
function

10

Conventional Methods:
LOC/FP Approach

t compute LOC/FP using estimates of
information domain values
t use historical effort for the project

11

Example: LOC Approach

12

Example: FP
Approach

13

Tool-Based Estimation

project characteristics
calibration factors
LOC/FP data

14

Empirical Estimation
Models
General form:

exponent
effort = tuning coefficient * size

usually derived
as person-months empirically
of effort required derived
usually LOC but
may also be
function point
either a constant or
a number derived based
on complexity of project

15

Estimation Guidelines

estimate using at least two techniques
get estimates from independent sources
avoid over-optimism, assume difficulties
you've arrived at an estimate, sleep on it
adjust for the people who'll be doing the
job—they have the highest impact

16

The Make-Buy Decision
simple (0.30) $380,000

$450,000
difficult (0.70)
build
$275,000
minor changes
(0.40)
reuse
system X $310,000
simple (0.20)
major
changes
buy (0.60) $490,000
complex (0.80)

minor changes $210,000
contract (0.70)

$400,000
major changes (0.30)

without changes (0.60) $350,000

$500,000
with changes (0.40)

17

Computing Expected
Cost
expected cost =
(path probability) x (estimated path cost)
i i
For example, the expected cost to build is:
expected cost build=
= 0.30($380K)+0.70($450K)
= $429 K
similarly,
expected cost reuse = $382K
expected cost buy = $267K
expected cost contr = $410K

18

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