Computers Are Your Future

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Dec 2, 2013 (3 years and 8 months ago)

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Computers Are Your Future

Eleventh Edition

Chapter 13: Systems Analysis & Design








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

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Systems Analysis & Design

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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.

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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.

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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 requirements

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System Analysts:
Communication Counts

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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

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The Systems Development
Life Cycle

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The Systems Development
Life Cycle


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

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The Systems Development
Life Cycle


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.


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The Systems Development
Life Cycle


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.


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The Systems Development
Life Cycle


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.



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The Systems Development
Life Cycle


Waterfall model


Builds correction
pathways into the
process


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

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The Systems Development
Life Cycle


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

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Phase 1: Planning the System


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

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Phase 1: Planning the System


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.

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Phase 1: Planning the System


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.

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Phase 1: Planning the System


A
Gantt chart
summarizes plans

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Phase 1: Planning the System


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)

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Phase 1: Planning the System


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.

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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.

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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.


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Design tools


Deliverable: Entity
-
relationship diagram


Phase 3: Designing the System


Design tools


Data flow diagram uses symbols for data
movement



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Phase 3: Designing the System


Design tools


Team members develop:


Project dictionary:

defines terminology


Data dictionary: identifies data types

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Phase 3: Designing the System


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.

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Phase 3: Designing the System


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

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Phase 3: Designing the System

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

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Phase 4:

Implementing the System


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.


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Phase 4:

Implementing the System


Training


Converting systems


Parallel conversion


Pilot conversion


Phased conversion


Direct (crash) conversion


The fully tested system is the
deliverable for phase 4.


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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

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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.


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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

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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.


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Summary


Deliverables from each phase of the
SDLC are input to the next phase:

1.
Project proposal

2.
Review of the present information system

3.
Review of the proposed information
system

4.
Fully tested finished result

5.
System evaluation after its implementation

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