IS 421 Information Systems Analysis James Nowotarski 4 November 2002

IS 421Information Systems Analysis

James Nowotarski

4 November 2002

• Recap data flow diagramming• Understand steps required for creating a work

plan• Discuss Assignment 5

Today’s Objectives

Course Map

Contents

1. Introduction

Planning Phase2. Project Initiation3. Project Management

Analysis Phase4. Systems Analysis5. Gathering Information6. Process Modeling7. Data Modeling

1 2 3 4 6 7 8 9 10 115

Assignments

QuizzesFinal

Week

CoreExamReview

Topic Duration

• Prof. Burns 30 minutes

• DFD Recap 30 minutes

• Quiz 45 minutes

*** Break 15 minutes

• Project management 45 minutes

• Assignment 5 Intro 15 minutes

Today’s agenda

Topic Duration



• Quiz 45 minutes




Today’s agenda

Process modeling

Prepare use cases

use case reports

Create DFDs

UsersUsers

data flow diagrams

businessprocess

info

• Easier for users to work with than DFDs

• Info gathered through interviews, JAD, etc.

To Design

DFD Balancing

0

SystemName

Input AEntity 1Entity 1

Entity 2Entity 2

Input B

Output CEntity 3Entity 3

DFD Balancing

Input A

1

General Process

AAA

Entity 1Entity 1

Entity 2Entity 2

Output C Entity 3Entity 3

Input B

3

General Process

CCC

2

General Process

BBB

4

General Process

DDD

Data Flow B

D1 Data Store 1 D2 Data Store 2

Data Flow D

Data Flow A

Data Flow A

Data Flow C

Data Flow C

Which is best?

CustomerCustomer Changeaddress

1Address change info

D1 Customer InformationAddress change info


1Address change info



1 Address info


Address change info

Scenario: A customer notifies a magazine publisher of a change of address.

“For clarity, it is better practice to draw two separate data flows” (p. 149)

• Manual vs. Automated processes• Chronological order• Can same external entity be shown more than

once (yes, to avoid crossing lines)

DFD Issues

DFD Step-by-Step(8) Grades are reported back to students via a course web page created from the spreadsheet.

Professor

CampusConnect

1

Downloadstudent info

Courseroster

Course roster 2

Maintainstudents

D2 StudentStudent info

Student info

3

Maintainassignments

D1 Assignment

Assignmentinfo

Assignment info

Students 4

Collectassignment

Completedassignment

Compeleted assigments

5

Distributeassignment

Assignment info

Assignmentinfo

Completed assignments

6

Gradeassignments

Assignmentinfo

Studentinfo

D3 Grade

Gradeinfo

Students

7

Reportgrade

Student id

Grade info

Gradeinfo

Topic Duration



• Quiz 45 minutes




Today’s agenda

Topic Duration



• Quiz 45 minutes




Today’s agenda

Project Management

Key Definitions

• Project management is the process of planning and controlling the development of a system within a specified timeframe at a minimum cost with the right functionality.

Management Challenges in Analysis

• Political difficulties– Especially in larger projects, where the new system will

serve several, possibly conflicting, interest groups• Communication problems

– People of different backgrounds, vocabularies being asked to work together

– Users in particular may struggle to understand the technical-looking outputs of the Analysis phase

• Scope management • Analysis paralysis

– Easy to become mired in detail, not know when to finish• “Prematurely physical”

Project Management (50K foot view)

Create Work plan

Staff the project

Controlproject work

Create the work plan

Usersrequirements 1

Negotiatereqts

negotiatedrequirements

2

Decom-pose

workbreakdownstructure

4

Estimateresources

workmonths

3

Estimatesize

deliverablesize

5

Developschedule

schedule

Iterate as necessary

Estimating a Project Based on Industry Information

Planning Analysis Design Implementation

IndustryStandardFor Web 15% 20% 35% 30%Applications

TimeRequired 4 5.33 9.33 8in PersonMonths

Some Courses at DePaul

• SE 468: Software Measurement and Estimation– Software metrics. Productivity, effort and defect models.

Software cost estimation. PREREQUISTE(S):CSC 423 and either SE 430 or CSC 315 or consent

• SE 477: Software and System Project Management– Planning, controlling, organizing, staffing and directing

software development activities or information systems projects. Theories, techniques and tools for scheduling, feasibility study, cost-benefit analysis. Measurement and evaluation of quality and productivity. PREREQUISTE(S):SE 465 or CSC 315

Estimation Trade-offs

• Time– Months

• Effort– Person-months

• Size– Function points

– Lines of code

Getting the Right Numbers for Estimation

• Prior projects– Past experience

– Industry standards

• Detailed analysis

Estimating Schedule Time

• Rule of thumb for estimation

Schedule Time (months)

=

3.0 * person-months1/3

Timeboxing

• Fixed deadline• Reduced functionality, if necessary• Fewer “finishing touches”

Timeboxing Steps

• Set delivery date

– Deadline should not be impossible

– Should be set by development group• Prioritize features by importance• Build the system core• Postpone unfinished functionality• Deliver the system with core functionality• Repeat steps 3-5 to add refinements and

enhancements

Margins of Error in Cost and Time Estimates

Typical margins of Error for

Well-done Estimates

Phase Deliverable Cost (%)time (%)

Planning System Request 400 60Project Plan 100 25

Analysis System Proposal 5015

Design System Specification 25 10

Source: Boehm et al. (1995)

Relative Cost to Fix an Error

It costs 50x more to fix an error discovered in production than in Analysis phase

Phase in which error detected

Analysis Design Code Unit test Acceptancetest

Production

0.1

0.2

0.5

1

2

5

10

20

50

Rel

ati v

e c o

s t t

o f

ix

Tracking Tasks Using Gantt Chart

Go to Library

Go to Bookstore

Select and Purchase Book

Skim Book

Write Phase One

Read Book Carefully

Write Phase Two

Action Week 2 3 4 5 6 7 8 9 10 11 12 13

CASE Tools

Initiation Analysis Design Implementation

Upper CASE Lower CASE

Integrated CASE (I-CASE)

Procedural MetadataLogic

Diagrams ScreenDesigns

CASE Repository

CASE Components

Standards

• Examples– Formal rules for naming files

– Forms indicating goals reached (see page 75)

– Programming guidelines

Documentation

• Project binder• Table of contents• Continual updating

Classic Mistakes

• Overly optimistic schedule• Failing to monitor schedule• Failing to update schedule• Adding people to a late project• Scope creep• Lack of change control

Topic Duration



• Quiz 45 minutes




Today’s agenda

End of slides

Documents

IS 421 Information Systems Analysis James Nowotarski 4 November 2002