1. For University Use Only
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.

2. Chapter 5 Software Project Planning

3. 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!

4. Objectives
Provide a framework that enables the manager to make reasonable estimates of resources, cost, and schedule
The attempt to determine
Money
Effort
Resources
Time ++

5. Risk on estimation Project complexity Project size
Degree of structural uncertainty
Availability of historical information ++

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

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

8. Software Scope Describes: Data & control Function Performance
Constraints
Interfaces
reliability ++

9. To Understand Scope ... Understand the customers needs
understand the business context
understand the project boundaries
understand the customer’s motivation
understand the likely paths for change
understand that ...
Even when you understand,
nothing is guaranteed!

10. Reusable software components Hardware/software tools
Resources
Hardware/software tools
Reusable software components
People
People
Reusable software components
Hardware/software tools ++

11. Software Project Estimation
Options:
Delay estimation until late in the project
Base estimates on similar projects
Use relatively simple decomposition techniques to generate project cost and effort estimates
Use one or more empirical models for software cost and effort estimation ++

12. 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

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

14. Accuracy of Estimate
The accuracy of software estimate is determined by:
Estimated size of the product
Ability to translate the size into effort, time and budget
The ability of software team meets the project plan
The stability of requirements and environment ++

15. Functional Decomposition
Statement
perform
of Scope a
"grammatical
parse"

16. Creating a Task Matrix Obtained from “process framework”
framework activities
application
functions
Effort required to accomplish
each framework activity for each application function

17. Conventional Methods: LOC/FP Approach
compute LOC/FP using estimates of information domain values
use historical effort for the project

18. LOC/FP What do LOC & FP oriented estimation have in common? ++
Bounded statement of software scope is decomposed to be estimated individually
Baseline productivity metrics (eg. LOC/PM, FP/PM) are then applied ++

19. LOC/FP – Differences
They differ in the level of detail of decomposition and the target of partitioning
For LOC estimates, decomposition focuses on software function (& its sub-functions)
For FP estimates, decomposition focuses on information domain characteristics (ie, input, output, data files, inquiries, & external interfaces) ++

20. Expected Value S = (Sopt + 4Sm + Spess)/6
Where Sopt, Sm, Spess is optimistic, most likely and pessimistic estimates ++

21. Example: LOC Approach

22. Example: FP Approach

23. Tool-Based Estimation
project characteristics
calibration factors
LOC/FP data

24. Empirical Estimation Models
General form:
exponent
effort = tuning coefficient * size
usually derived
empirically
as person-months
derived
of effort required
usually LOC but
may also be
function point
either a constant or
a number derived based
on complexity of project

25. Empirical Estimation Models – Examples
Boehm simple model
E = a * (KLOC)b
D = 2.5 (E)d
Coefficient table
S/W Project ab bb db
Organic
2.4
1.05
0.38
Semi detached
3.0
1.12
0.35
Embedded
3.6
1.20
0.32

26. 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

27. The Make-Buy Decision Acquisition options:
Software may be purchased (or licensed) off-the-self
“full-experience” or “partial-experience” software components may be acquired and modified
Software may be custom built by outside contractor ++

28. Decision Tree Analysis

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

30. Outsourcing
Software engineering activities are contracted to a third party who does the work at lower cost and, hopefully, higher quality
Outsourcing decision is often a financial one
+- …
Positive side: cost saving
Negative side: lose some control ++

31. Automated Estimation Tools
Sizing of project deliverables
Selecting project activities
Predicting staffing levels
Predicting software effort
Predicting software cost
Predicting software schedules ++