1 introduction to systems development life cycle

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Introduction to Systems Development Life Cycle

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The Information Systems Life Cycle

What are the four steps in the information systems life cycle (ISLC)?

1. System development

2. System implementation

3. Syetem Operation

4. System obsolencence

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The Systems Development Life Cycle

What are the five steps in the systems development life cycle (SDLC)?

1. Systems analysis

2. Conceptual design

3. Physical design

4. Implementation and conversion

5. Operations and maintenance

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The Systems Development Life Cycle: Systems Analysis

Systems Analysis Do initial investigation Do system survey

Do feasibility study Determine information needs

and system requirements Deliver systems requirements

Conceptual Design

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The Systems Development Life Cycle: Conceptual Design

Conceptual Design Identify and evaluate design alternatives

Develop design specifications Deliver conceptual design

requirements

Physical Design

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The Systems Development Life Cycle: Physical Design

Physical Design Design output Design database Design input Develop programs

Develop procedures Design controls

Deliver developed system

Implementation and Conversion

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The Systems Development Life Cycle: Implementation and Conversion

Implementation and Conversion Develop plan

Install hardware and software Train personnel, test the system

Complete documentation Convert from old to new system

Fine-tune and review Deliver operational system

Operation and

Maintenance

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The Systems Development Life Cycle: Operation and Maintenance

Operation and Maintenance Operate system

Modify system Do ongoing maintenance Deliver improved system

SystemsAnalysis

Feasibility analysis and decision points:

Economic Feasibility

Technical Feasibility

Legal Feasibility

Scheduling Feasibility

Operational Feasibility

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The Players

Who are the people involved in developing and implementing IS?Management Information systems steering

committeeProject development teamSystems analysts and programmersExternal players

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The Players

What are top management’s roles?– providing support and encouragement– establishing system goals and

objectives– determine information requirements

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The Players

What are the steering committee’s roles?– set policies that govern the IS– ensures top-management participation– guidance and control– facilitates coordination and integration

of IS activities

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The Players

What are the project development team’s roles?– plan each project– monitor project – make sure proper consideration is

given to the human element

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The Players

What are the system analyst’s and programmer’s roles?– study existing systems– design new systems and prepare

specifications– write computer programs

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Planning Systems Development

Why is planning an important step in systems development?– consistency– efficiency– cutting edge– lower costs– adaptability

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Planning Systems Development

What types of systems development plans are needed?– project development plan– master plan

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Planning Techniques Two techniques for scheduling and

monitoring systems development activities are:1 PERT (program evaluation and review

technique)• PERT requires that all activities and the precedent

and subsequent relationships among them be identified.

2 Gantt chart• A bar chart with project activities listed on the left-

hand side and units of time across the top

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Planning Techniques: Gantt Chart

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Activity Week Starting12345678

Project Planning Chart (Sample Gantt Chart)

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Gantt Chart

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PERT Chart

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Microsoft Project Gantt Chart

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Microsoft Project PERT Chart

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Feasibility Analysis

Systems analysis is the first step in the systems development life cycle (SDLC).

A feasibility study (also called a business case) is prepared during systems analysis and updated as necessary during the remaining steps in the SDLC.

The steering committee uses the study to decide whether to terminate a project, proceed unconditionally, or proceed conditionally.

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Feasibility Analysis

What five important aspects need to be considered during a feasibility study?

1. Technical feasibility

2. Operational feasibility

3. Legal feasibility

4. Scheduling feasibility

5. Economic feasibility

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Feasibility Analysis

Economic feasibility is the most frequently analyzed of the five aspects.

What is the basic framework for feasibility analysis?– capital budgeting model

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Feasibility Analysis

What are some capital budgeting techniques?– payback period– net present value (NPV) – internal rate of return (IRR)

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Candidate Systems Matrix

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Candidate Systems Matrix (cont.)

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Feasibility Matrix

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Typical System Proposal Outline

I. Introduction

A. Purpose of the report

B. Background of the project leading to this report

C. Scope of the report

D. Structure of the report

II. Tools and techniques used

A. Solution generated

B. Feasibility analysis (cost-benefit)

III. Information systems requirements

IV. Alternative solutions and feasibility analysis

V. Recommendations

VI. Appendices

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Behavioral Aspects of Change

Individuals involved in systems development are agents of change who are continually confronted by people’s reaction and resistance to change.

The best system will fail without the support of the people it serves.

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Behavioral Aspects of Change Why do behavioral problems occur?

– personal characteristics and background

– manner in which change is introduced– experience with prior changes– communication– disruptive nature of the change

process– fear

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Behavioral Aspects of Change

How do people resist IS changes?– aggression– projection– avoidance

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Behavioral Aspects of Change How can behavioral problems be

overcome?– meet needs of the users– keep communication lines open– maintain a safe and open atmosphere– obtain management support– allay fears– solicit user participation– make sure users understand the system

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Behavioral Aspects of Change– How can behavioral problems be

overcome? (continued)– provide honest feedback– humanize the system– describe new challenges and opportunities– reexamine performance evaluation– test the system’s integrity– avoid emotionalism– present the system in the proper context– control the users’ expectations– keep the system simple

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Systems Analysis

When a new or improved system is needed, a written request for systems development is prepared.

The request describes the current system’s problems, why the change is needed, and the proposed system’s goals and objectives.

It also describes the anticipated benefits and costs.

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Sample Request for System Services

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Sample Problem Statements

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Systems Analysis

There are five steps in the analysis phase:

1. Initial investigation

2. Systems survey

3. Feasibility study

4. Information needs and systems requirements

5. Systems analysis report

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Computer-Aided Software Engineering (CASE) CASE is an integrated package of

computer-based tools that automate important aspects of the software development process.

CASE tools are used to plan, analyze, design, program, and maintain an information system.

They are also used to enhance the efforts of managers, users, and programmers in understanding information needs.

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Computer-Aided Software Engineering (CASE) CASE tools do not replace skilled

designers; instead they provide a host of self-integrated tools that give developers effective support for all SDLC phases.

CASE software typically has tools for strategic planning, project and system management, database design, screen and report layout, and automatic code generation.

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CASE Tool Architecture

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Computer-Aided Software Engineering (CASE)

Advantages of CASE Technology

Improved productivity Improved program quality

Cost savings Improved control procedures

Simplified documentation

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Computer-Aided Software Engineering (CASE)

Disadvantages of CASE Technology Incompatibility

CostUnmet expectations

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Systems Design, Implementation, and Operation

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Conceptual Systems Design

In the conceptual systems design phase, a general framework is developed for implementing user requirements and solving problems identified in the analysis phase.

What are the three steps in conceptual design?

1. Evaluate design alternatives.2. Prepare design specifications.3. Prepare conceptual systems design report.

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Conceptual Systems Design

Systemsanalysis

Prepareconceptual

systemsdesign report

Preparedesign

specifications

Evaluatedesign

alternatives

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Conceptual Systems Design

Evaluate design alternatives: The design team should identify and

evaluate design alternatives using the following criteria:

1. How well it meets organizational and system objectives

2. How well it meets users’ needs

3. Whether it is economically feasible

4. Its advantages and disadvantages

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Conceptual Systems Design

Prepare design specifications: Once a design alternative has been

selected, the team develops the conceptual design specifications for the following elements:

1. Output

2. Data storage

3. Input

4. Processing procedures and operations

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Conceptual Systems Design

Prepare conceptual systems design report:

At the end of the conceptual design a conceptual systems design report is developed and submitted.

1. To guide physical systems design activities

2. To communicate how management and user information needs will be met

3. To help assess systems’ feasibility

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Physical Systems Design

Physical design translates the broad, user-oriented AIS requirements of conceptual design into detailed specifications that are used to code and test the computer program.

Conceptualsystems design

Physicalsystems design

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Physical Systems Design: Output Design

The objective of output design is to determine the characteristics of reports, documents, and screen displays.

Output fits into one of four categories:

1. Scheduled reports

2. Special-purpose analysis

3. Triggered exception reports

4. Demand reports

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Physical Systems Design: File and Database Design

What are some file and database design considerations?– medium of storage– organization and access– processing mode– maintenance– size and activity level

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Physical Systems Design: Input Design When evaluating input design, the

design team must identify the different types of data input and optimal input method.

What are the two principal types of data input?

1. Forms

2. Computer screens

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Physical Systems Design: Program Design Program design is one of the most time-

consuming activities in the entire SDLC. Programs should be subdivided into small,

well-defined modules to reduce complexity. What is this referred to as?

– structured programming Modules should interact with a control

module rather than with each other.

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Physical Systems Design: Procedures Design Procedures design should answer the

who, what, where, and how questions related to all AIS activities.

What should procedures cover? input preparation transaction processing error detection and corrections controls

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Physical Systems Design: Procedures Design

What should procedures cover? (continued)

reconciliation of balances database access output preparation and distribution computer operator instructions

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Physical Systems Design: Control Design

What are some control design considerations?

Validity Authorization

Accuracy Security

Numerical Control Availability

Maintainability IntegrityAudit Control

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Physical Systems Design Report

At the end of the physical design phase the team prepares a physical systems design report.

This report becomes the basis for management’s decision whether to proceed to the implementation phase.

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Systems Implementation

Systems implementation is the process of installing hardware and software and getting the AIS up and running.

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Systems ImplementationImplementation planning

Completedocumentation

Develop andtest software

programs

Conversion

Prepare site;install and

test hardware

Selectand trainpersonnel

Test system

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Systems Implementation: Implementation Planning

An implementation plan consists of implementation tasks, expected completion dates, cost estimates, and the person or persons responsible for each task.

Planning should include adjustments to the company’s organizational structure.

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Systems Implementation: Develop and test software programsSeven steps are followed when developing

and testing software programs.1. Determine user needs.

2. Develop a plan.

3. Write program instructions (code).

4. Test the program.

5. Document the program.

6. Train program users.

7. Install and use the system.

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Systems Implementation: Site Preparation

A PC requires little site preparation. A large system may require extensive

changes, such as additional electrical outlets.

Site preparation should begin well in advance of the installation date.

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Systems Implementation: Select and train personnel

Employees can be hired from outside the company or transferred internally.

Effective AIS training should include employees’ orientation to new policies and operations.

Training should occur before systems testing and conversion.

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Systems Implementation:Complete Documentation

Three types of documentation must be prepared for new systems.

1. Development documentation

2. Operations documentation

3. User documentation

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Systems Implementation: Test the System

There are three common forms of testing.

1. Walk-through

2. Processing of test transactions

3. Acceptance tests

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Systems Implementation: Conversion

There are four conversion approaches.

1. Direct conversion

2. Parallel conversion

3. Phase-in conversion

4. Pilot conversion

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Systems Implementation

Old system

New system

Direct Conversion Method

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Systems Implementation

Old system New system

Parallel Conversion Method

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Systems Implementation

Phase-in Conversion Method

Old system

New system

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Systems Implementation

Pilot Conversion Method

1 2 3 31 2

33 22 11

Old Old Old Old Old New

Old New New New New New

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Systems Implementation: Data Conversion

Data files may need to be modified in three ways:

1. Files may be moved to a different storage

2. Data content may be changed

3. File format may be changed

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Operation and Maintenance

The final step in the SDLC is to operate and maintain the new system.

A postimplementation review should be conducted on a newly installed system.

Operation andmaintenance

Implementationand conversion

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Operation and MaintenanceWhat are some factors to consider during the postimplementation review?

Goals and objectives

Satisfaction

Benefits

Costs

Reliability

Documentation

Timeliness

Controls and security

Errors

Training

Communications

Organizational changes

Accuracy

Compatibility