Chapter05 software project planning RPL

8/10/2019 Chapter05 software project planning RPL

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

Chapter 5Software Project Planning


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Software Project Planning

The overall goal of project planning is

to establish a pragmatic strategy forcontrolling, tracking, and monitoring acomplex technical project.

Why?

So the end resu l t gets don e on t ime,

w i th qual i ty!


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The Steps

Scopingunderstand the problem and

the work that must be doneEstimationhow much effort? how

much time?

Riskwhat can go wrong? how can we

avoid it? what can we do about it?Schedulehow do we allocate

resources along the timeline? what arethe milestones?

Control strategyhow do we controlquality? how do we control change?


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Write it Down!

SoftwareProject

Plan

Project ScopeEstimatesRisks

ScheduleControl strategy


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To Understand Scope ...

Understand the customers needs

understand the business context

understand the project boundaries

understand the customers motivation

understand the likely paths for change

understand that ...

Even when you understand,

no th ing is guaranteed!


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Cost Estimation

project scope must be explicitlydefinedtask and/or functionaldecomposition is necessaryhistorical measures (metrics) arevery helpful

at least two different techniquesshould be usedremember that uncertainty isinherent


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Estimation Techniques

past (similar) project experience

conventional estimation techniques task breakdown and effort estimates

size (e.g., FP) estimates

tools (e.g., Checkpoint)


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Functional Decomposition

Statementof Scope

performa

"grammatical

parse"

functionaldecomposition


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Creating a Task Matrix

Obtained from process framework

application

functions

framework activities

Effort required toaccomplisheach frameworkactivity for eachapplication function


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Conventional Methods:LOC/FP Approach

compute LOC/FP using estimates ofinformation domain values

use historical effort for the project


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Example: LOC Approach

Functions

UICF

2DGA

3DGA

DSM

CGDF

PCF

DAM

Totals

estimated LOC $/LOC Cost Effort (months)LOC/pm

2340

5380

6800

3350

4950

2140

8400

33,360

14

20

20

18

22

28

18

315

220

220

240

200

140

300

32,000

107,000

136,000

60,000

109,000

60,000

151,000

655,000

7.4

24.4

30.9

13.9

24.7

15.2

28.0

145.0


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Example: FP Approach

number of user inputs

number of user outputs

number of user inquiries

number of files

number of ext.interfaces

algorithms

measurement parameter

4

5

4

7

7

3

count

x

x

x

x

x

x

count-total

=

=

=

=

=

=

weight

complexity multiplier

feature points

0.25 p-m / FP = 120 p-m

40

25

12

4

4

60

160

125

48

28

28

180

569

.84

478


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Tool-Based Estimation

project characteristics

calibration factors

LOC/FP data


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Empirical Estimation Models

General form:

effort = tuning coefficient * sizeexponent

usually derivedas person-monthsof effort required

either a constant ora number derived based

on complexity of project

usually LOC butmay also befunction point

empiricallyderived


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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 thejobthey have the highest impact


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The Make-Buy Decision


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Computing Expected Cost

(path probability) x (estimated path cost)i i

For example, the expected cost to b ui ld is:

expected cost = 0.30($380K)+0.70($450K)

simi lar ly,

expected cost = $382K



build

reuse

buy

contr

expected cost =

= $429 K

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Chapter05 software project planning RPL