Systems Analysis and Design:The Big Picture

Computers:Tools for an Information Age

ObjectivesDefine the terms “system,” “analysis,” and “design”Describe the principal functions of the systems analystList and describe the phases of the systems development life cycleDescribe the various data-gathering and analysis toolsDescribe a selection of systems design toolsExplain the concept of prototypingExplain the role of the maintenance task in the systems development life cycle

Systems Analysis DesignSystem – an organized set of related components established to accomplish a certain task Computer system – a system that has a computer as one of

its components

Analysis - Studying an existing system to determine how it works and how it meets users’ needs Typically happens as a result of some impetus for change,

combined with the authority to make the change

Design - The process of developing a plan for an improved system, based on the result of the systems analysis

Who Participates?

ProjectTeam

Key Individuals Involved in Systems Analysis

Systems analyst – performs analysis and designMay perform some programming as well

Client – the person or organization contracting to have the work done

User – the people who will have contact with the system

Systems Analyst: A Change AgentThe catalyst or persuader who overcomes the reluctance to change within an organizationSystems analyst can function as change agent, but it works best if it is someone inside the organization What it takes: Coordination of many people, tasks, and schedules Communication skills, both oral and written Planning and design (an analytical mind)

Self-discipline and self-direction Good organizational skills Creativity The ability to work without tangible results

System Development Life Cycle (SDLC)

Organized set of activities that guides those involved through the development

of an information system.

Phases Preliminary Investigation Analysis Design Development (Documentation) Implementation

Ongoing activities Project management Overall

Documentation Information gathering

Preliminary InvestigationOr feasability study•Problem Definition

Development and testing.•Scheduling•Programming

Implementation•Training•Conversion•Evaluation•Maintenance

Analysis•Gather data•Analyze data•Develop requirements

Design•Preliminary design•Detail design

Ongoing Activities•Project Management•Documentation•Information Gathering.

Systems Development Life Cycle

•Documentation

System Development Guidelines

Use a structured approach

Involve the Users

Develop Standards

Ongoing Activity: Project Management

The process of planning, scheduling, and controlling activities during the SDLC

Scope (goal, objectives, expectations)

Activities and Deliverables to be completed

Time estimates

Cost estimates

Order activities occur

Activities performed concurrentlyGantt Chart

Project Plan

Ongoing Activity: Feasibility AssessmentMeasure of how suitable the development of a system will be in the

organization. (Initially occurs in the Preliminary Investigation phase but needs to be continuously reevaluated)

Operational feasibility

Schedule feasibility

Technical feasibility

Economic or cost/benefit feasibility

Ongoing Activity: Documentation

Compilation and summarization of data and informationReports

DiagramsProgramsOther deliverables generated during SDLC

Project NotebookProject Dictionary/Repository

Ongoing Activity: Data & Info Gathering

Review current system documentation

Observe

Send Questionnaires

Interview Structured/Unstructured

Conduct JAD (joint application design) sessions

Research

Begins in Analysis Phase, but is continually updated

Phase 1: Preliminary Investigation

A brief study of the problem to determine A brief study of the problem to determine whether the project should be pursuedwhether the project should be pursued

•Also called the feasibility study or system Also called the feasibility study or system surveysurvey

•Involves working with the usersInvolves working with the users

•Organization chart – a hierarchical drawing Organization chart – a hierarchical drawing showing the organization’s managementshowing the organization’s management

Feasibility StudyTechnical feasibility

Economic feasibility

Operational feasibility are the current work practices and procedures

adequate to support the new system? Legal feasibility

Schedule feasibility how long will the system take to develop, or can it

be done in a desired time-frame?

Defining the Problem

Two points that must be agreed upon The nature of the problem The scope (boundaries) of

the problem

Agreeing on the problem helps define the objectives of the system

Project Request

Feasibility Assessment

Feasibility Assessment

(continued)

Phase 2: Analysis

Understand the existing system

Two tasks are involvedData gatheringData analysis

Data Gathering

A number of techniques can be used Interviews with users and managers

Structured interview – includes only questions that have been written out in advance

Unstructured interview – interviewer has a general goal but few, if any questions prepared

Examining current business and systems documents and output

may include current order documents, computer systems procedures and reports used by operations and senior management

Sending out questionnaires Observation of current procedures

by spending time in various departments; a time and motion study can show where procedures could be more efficient, or to detect bottlenecks

Data Analysis

Typical tools for data analysisEntity Relationship diagramData flow diagramDecision table/Decision TreeWritten report

Report to management/ customer/ client

Entity-Relationship Diagrams (ERD)

Tool to graphically represent the associations between entities in the project

Noun

Verb

Data Flow Diagrams (DFD)Tool to graphically represent the

flow of data in a system

Process

Sour

ce

Data Flow

Data Store

Decision Table

Decision Tree

System Requirements & recommendations

A detailed list of things the system must be able to do Highlight problems with current system The design of the new system will be based on these

requirements Analyst and management must come to a clear

agreement on requirements List of possible solutions Hardware/software recommendations

Report to Management

Summarizes the problems found in the current system

Describes the requirements for the new system, including a cost analysis

Makes a recommendation on what course to take next

Pre-Design considerationsThe hardware platform which type of computer, network

capabilities, input, storage and output devices

The software programming language, package or

database

The outputs report layouts and screen designs

The inputs documents, screen layouts, validation

procedures

The user interface how users will interact with the

computer system

The modular design of each program in the application

The test plan and test dataConversion plan how the new system is to be

implemented

Documentation User Technical

Phase 3: DesignThe new system is actually planned

Divided into two subphasesPreliminary design

Several key decisions must be madeDetail design specifications

Output requirements Input requirementsFiles and databasesSystem processingSystem controls and backups

Build or Buy?

Custom Software Developed by user Developed at user

request by outside vendor

Packaged Software Horizontal

Many org types

Vertical Industry specific

Acquire Hardware/Software

Technical specifications

Solicit vendor proposals

Test & evaluate Benchmark Test

Make a decision

Input OutputThings to consider The medium (paper,

screen, etc.) of the output

The types of reports needed and what data is needed for the reports

Things to consider The input medium

(captured at the source, keyed from source document)

The fields needed, how they are laid out on the input screen, etc.

Input validation may be necessary

Requirements

Input/Output Design

Mockup(User)

Layout Chart(Programmer)

Files and Databases

Things to considerHow files are organized

Sequentially, directly, or by another methodThe format of the records making up the

data files

Database Design

Table structure definitions & relationships

Security

Program DesignData Entry

Program

File

Hard copy

Comment

Flow ChartSystem Processing

Phase 4: Development

Schedule and monitor the two principal activities Programming Testing

There are several project scheduling tools available

Programming

Prepare program design specifications

Use logic flowcharts and pseudocode to facilitate code development

Testing

Unit testing – verifies that individual program units workPerform testing with test data

System testing – determines whether all program units work together as plannedVolume testing – uses real data in large amountsDetermines whether the system can handle

a large volume of data

Phase 5: Implementation

Steps involved in starting the new systemTrainingEquipment conversionFile conversionSystem conversionAuditingEvaluationMaintenance

Training

Teach users how to use the systemThe system will do no better than the

people using itDevelop user’s manual to aid users who

are not familiar with the systemHands-on training is best

Equipment Conversion

Items to considerDelivery schedules must be

coordinatedTerminals or personal computers

must be networkedDevices on the system must be

compatible

File Conversion

If existing files are manual, they must be keyed in or scanned into the systemManual files must be kept current while

data is being input into the new system

If existing files are computer-based, programs must be written to convert the files into the format needed for the new system

System Conversion

Four approaches Direct conversion – the user simply stops using

the old system and starts using the new one Phased conversion – the system is implemented

one part at a time Pilot conversion – the entire system is used by a

designated set of users Parallel conversion – the old and new systems are

both used until users are satisfied the new system works

Conversion Options

Auditing

Systems to trace data in the system back to a source documentVery helpful in tracing security violations

Evaluation

Determines how well the system is meeting the original requirements, benefits, and budgetsEvaluation can be performed by the

analyst and someone from the organizationEvaluation can also be performed by an

independent third party

Maintenance

An ongoing activity that lasts the lifetime of the system

Several types of maintenance activitiesEnhancements to the systemFix bugs in the system as they are

identified

Terms to Know: Chapter 14AnalysisBenchmark testBuild-or-buy decisionCASE Cost/benefit analysisData dictionaryData flow diagramDecision tree/Decision tableDeliverableDesignDevelopmentDirect conversionDocumentationEntity-relationship diagram (ERD)Feasibility Assessment/StudyGantt chartJoint application development (JAD)Layout chartMockup

OutsourcingParallel conversion

Phased conversion

Pilot conversionPost-implementation system reviewPreliminary investigationProject dictionaryProject planPrototypeRFP, RFQ, RFIScopeSystemSystem designSystem development life cycle-SDLCSystem testingSystems analystUnit testingVolume testing

If asked, can you…Define the terms “system,” “analysis,” and “design”Describe the principal functions of the systems analystList and describe the phases of the systems development life cycleDescribe the various data-gathering and analysis toolsDescribe a selection of systems design toolsExplain the concept of prototypingExplain the role of the maintenance task in the systems development life cycle

Sources

Capron; Computers: Tools for An Information Age, 8th Ed. 2003

Pfaffenberger; Computers in Your Future 2003

Microsoft Clipart