Computers Are Your Future Eleventh Edition Chapter 13: Systems Analysis & Design Copyright © 2011...

Computers Are Your FutureEleventh Edition

Chapter 13: Systems Analysis & Design

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 1

Systems Analysis & Design


Objectives

Explain what systems analysts do. Understand the concept of a

system and its life cycle. Discuss why the systems

development life cycle (SDLC) is so widely used.

List the five phases of the SDLC.


Objectives

Describe the classic mistakes of failed information systems development projects and how systems analysts can avoid them.

Discuss the activities in each of the five phases of the SDLC.

Name the deliverables of each of the five phases of the SDLC.


System Analysts: Communication Counts

Systems analysis Involves information systems planning,

development, and implementation Is performed in an organized manner

Systems analysts Have good listening and communication

skills Work with users and management Determine information system

requirementsCopyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 5

System Analysts: Communication Counts


The Systems Development Life Cycle

Systems development life cycle (SDLC) Provides a systematic approach to

development Seeks to improve system quality Consists of five phases



System Is a collection of components working

together to achieve a goal Has a life cycle that starts with

creation, goes through growth and changes, and ends with obsolescence

Artificial system Developed by people rather than by

nature Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 9


System development life cycle philosophy Don’t proceed to the next

phase before the current one works properly.

Each phase must provide a deliverable that often serves as the input for the next phase.



Avoid mistakes Involve users to ensure that the

system meets their needs. Use a problem-solving methodology

to provide effective results. Use strong project management

skills.



Avoid mistakes Document all important facts about a

project. Use checkpoints to keep work on

target. Anticipate future growth and change

while designing the system.



Waterfall model Builds correction

pathways into the process

Allows the team to return to a previous phase if problems develop in later phases



Modern approaches Prototyping is a small-scale mock-

up of a system but has some problems:

Incomplete analysis User confusion Time consuming

Joint application development Conducts SDLC phases 1–4 at the same

time Involves intense team member

interaction


Phase 1: Planning the System

Recognizing the need for a system may come from acknowledging deficiencies.



Defining the problem Know the difference between a

symptom and a problem: Symptom—An acceptable result of a

problem Problem—The underlying cause of a

symptom

Examining alternative solutions Complete a requirements analysis

to identify the requirements based on needs.

Consider possible solutions.



Developing a plan Identify the appropriate solution. Create a project plan:

Cite the goals of the system. List activities for successful project

completion: Specify order of completion. Estimate time frames.

Create specifications.



A Gantt chart summarizes plans



Determining feasibility Technical feasibility: Can be completed

with existing technology Operational feasibility: Can be

accomplished with available resources Economic feasibility:

Can be done with available fiscal resources Often involves a cost-benefit analysis Seeks a return on investment (ROI)



Preparing the project proposal Project leader writes a report:

Identifies the problem. Explains the proposed solution and

benefits. Gives details of the plan. Concludes with a recommendation.

The project proposal is the deliverable for phase 1.


Phase 2: Analyzing & Documenting the Existing System

Analyzing the existing system Identify activities that need to be

retained. Uncover problems not evident in phase

1. Determining the new system

requirements State the requirements precisely. Provide a list as the deliverable from

phase 2.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 21

Phase 3: Designing the System

Explains how the new system will work Shows data path and procedures in

graphical tools Entity-relationship diagrams (ERDs) Data flow diagrams Project dictionaries

The phase 3 deliverable is a logical diagram or design.



Design tools Deliverable: Entity-relationship

diagram


Design tools Data flow diagram uses symbols for

data movement



Design tools Team members develop:

Project dictionary: defines terminology Data dictionary: identifies data types



Other design approaches Rapid application development

(RAD) Also known as prototyping. Create a small mock-up of system early in

the process. Provide enough functionality to get

feedback from users. Advantage: Users have something concrete

to review.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 26


Other design approaches Computer-Aided Software

Engineering (CASE) Used for complex systems Automates documenting entity relationships

and data flow Includes project management features, data

dictionaries, documentation support, and graphical output support



Phase 4: Implementing the System

Deciding whether to build or buy Develop in-house

Allows customization Is often more expensive

Purchase from outside vendor Purchase off the shelf and customize Outsource for specialized system creation



Developing the software A subset of the systems development

Testing Acceptance testing is performed by

the users and ensures that the system works properly.

Application testing involves assessing the programs separately and as a group.



Training Converting systems

Parallel conversion Pilot conversion Phased conversion Direct (crash) conversion

The fully tested system is the deliverable for phase 4.


Phase 5: Maintaining the System

Perform postimplementation system review. Evaluates whether the goals of the

system have been met Must meet the needs of the users. Must function properly.

Serves as the phase 5 deliverable


Summary

Systems analysts work with users and management to develop a system.

A system is a group of interrelated components that accomplish a goal. A system requires modification over time.

The SDLC provides structure to the development of the goal.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice

Hall 32

Summary

The five phases of the system development life cycle are:

Planning the system Analyzing and documenting the

existing information system Designing the system Implementing the system Maintaining the system


Summary

Lack of user involvement, poor project management, and lack of documentation cause projects to fail.

The SDLC phases should be completed in order with the results of one phase becoming the starting point for the next phase of the cycle.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice

Hall 34

Summary

Deliverables from each phase of the SDLC are input to the next phase:1. Project proposal2. Review of the present information

system3. Review of the proposed information

system4. Fully tested finished result5. System evaluation after its

implementation Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 35

Computers Are Your Future Eleventh Edition Chapter 13: Systems Analysis & Design Copyright © 2011...

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