ppt_03_System Dev.pdf

8/10/2019 ppt_03_System Dev.pdf

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LAST WEEK LESSON


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SUMMARY

Weve learned about the basic business activities

in which an organization engages, the decisions

that need to be made, and the information required

to make those decisions.

Weve reviewed the data processing cycle and its

role in organizing business activities and

providing information to users.

Finally, weve touched on the role of theinformation systems in modern organizations and

introduced the notion of enterprise resource

planningsystems.


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Basic Business Activities

Expenditure

Cycle

Human

Resources

ProductionCycle

RevenueCycle

Financing

Cycle

General Ledger & Reporting System


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ERP Systems


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C HAPTER 20 DAN 22

Systems Development

Process


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Learning Objectives

1. Explain the five phases of the systems developmentlife cycle.

2. Discuss the peopleinvolved in systems development

and the roles they play.3. Explain the importanceof systems development

planning and describe planning techniques.

4. Explain why system changes trigger behavioralreactions,

What form this resistance to change takes, and how to avoid or minimize the resulting problems.

5. Discuss the key issues and steps in system analysis.


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INTRODUCTION

As the environment, technology, and

competition change, an information

system must continually undergo changes

These changes range from minor

adjustments to major overhauls.

Occasionally the old system is scrapped

and replaced.


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INTRODUCTION

Companies change their systems for a variety ofreasons: To respond to changes in user needs or business needs

To take advantage of or respond to technology changes

To accommodate improvements in their businessprocess

To gain a competitive advantage and/or lower costs

To increase productivity

To accommodate growth To accommodate downsizing or distribute decision

making

To replace a system that is aged and unstable


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Learning Objective 1

Explain the five phases of the systemsdevelopment life cycle.


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SYSTEMS DEVELOPMENT LIFE CYCLE

The five stages (Mulyadi: three steps) inthe systems development life cycle are:

System Analysis

Conceptual Design Physical Design

Implementation and Conversion

Operation and Maintenance


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Systems Development Life Cycle (SDLC)

SystemAnalysis

ConceptualDesign

Physical DesignImplementation& Conversion

Operations &Maintenance


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Discuss the people involved in systemsdevelopment and the roles they play.


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THE PLAYERS

Many people are involved in developing andsuccessfully implementing an AIS, including:

Top management

Accountants The information systems steering committee

The project development team

Systems analysts

Computer programmers External players


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THE PLAYERS

Many people are involved in developing andsuccessfully implement an AIS, including:

Top management



Systems analysts



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THE PLAYERS

Top managements role in systemsdevelopment is to: Provide support and encouragement and a clear

signal that user involvement is important.

Help align the systems with corporate strategies.

Establish system goals and objectives.

Review IS department performance and leadership.

Establish policies for project selection and

organizational structure. Participate in important systems decisions.


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THE PLAYERS

User management needs to: Determine information requirements for departmental

projects.

Assist systems analysts with project cost-benefit

estimates.

Assign key staff members to development projects.

Allocate funds.


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THE PLAYERS


Top management



Systems analysts



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THE PLAYERS

Accountants also play an important role insystems development: As AIS users, they must determine their information needs

and systems requirements and communicate them to

system developers. As members of project development teams or steering

committees, they help management in the developmentprocess.

They are also active in:

Designing system controls and monitoring and testing thesecontrols.

Ensuring the system is easy to audit.

Controls and auditability need to be built in early tominimize costs and inefficiencies later.


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THE PLAYERS


Top management



Systems analysts



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THE PLAYERS

The information systems steering committee isan executive-level committee whose duty is toplan and oversee the IS function. Consists of high level management, such as:

Controller

IS Manager

User department managers

Sets policies to govern the AIS and assure top-

management participation, guidance, and control. Attempts to encourage goal congruence and reduce

goal conflict.


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THE PLAYERS


Top management



Systems analysts



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THE PLAYERS

The project development team includes systemsspecialists, managers, accountants, auditors, and userswhose responsibility is to guide development

Their job:

Plan each project. Monitor to ensure timely and cost-effective completion.

Ensure the human element is considered.

Communicate project status to top management and steeringcommittee.

Communicate and meet with users to: Consider ideas

Discuss progress

Eliminate surprises

The team approach produces more effective results and betteruser acceptance.


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THE PLAYERS


Top management



Systems analysts



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THE PLAYERS

Systems analysts study existing systems,design new ones, and preparespecifications that are used by

programmers. They interact with technical personnel and

users to bridge the gap.

They are responsible for ensuring the system

meets user needs.


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THE PLAYERS


Top management



Systems analysts



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THE PLAYERS

Computer programmers write thecomputer programs, using the specsdeveloped by the systems analysts.

They also modify and maintaining existingprograms.


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THE PLAYERS


Top management



Systems analysts



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THE PLAYERS

External players include:

Customers

Vendors

Auditors Governmental entities

Their needs must also be met in systems

development.


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Explain the importance of systemsdevelopment planning and describe

planning techniques.


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PLANNING SYSTEMS DEVELOPMENT

Several activities must be performed at varioustimes throughout the SDLC.

One of these activities is planning.

The organization should have plans for: The long range

Each systems development project

Each phase of each systems development project

Well discuss these plans and a number oftechniques to develop them.


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Systems development planning is an importantstep for the following key reasons: Consistencywith the organizations strategic plan.

Efficiencyachieved through coordination of thesubsystems.

Cutting edgetechnology and techniques.

Lower costsdue to lack of duplication, wasted effort,time overruns, and cost overruns.

Adaptabilityfor future changes.


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Two types of systems development plansare needed:

- Individual project plans developed by the

project teams.- A master plan developed by the IS steering

committee.


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committee.


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Individual project plans contain: A cost-benefit analysis.

Developmental and operational requirements,including:

Human resources

Hardware

Software

Financial resources

A schedule of activities to develop and operate thenew application


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committee.


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A master plan specifies: What the system will consist of

How it will be developed

Who will develop it

How needed resources will be acquired

Where the AIS is headed

It also provides:

Status of projects in process Prioritization of planned projects and criteria forestablishing priorities

Timetables for development


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Projects with highest priority are first to bedeveloped. These decisions are made by top management.

Planning horizon: About a 3-year horizon

With updates at least 2-3 times/yeareven morefrequently in some companies.

The CIO should determine: How soon technologies will be in wide use

Whether the company should adopt late or early

What business opportunities might arise from newtechnologies


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Planning Techniques

Two techniques for scheduling and

monitoring systems development

activities are:

Program Evaluation and Review Technique

(PERT)

Gantt Charts


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Planning Techniques


monitor systems development activities

are:

Program Evaluation and Review

Technique (PERT)

Gantt Charts


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A PERT diagram requires that all activities

in a project be identified along with the

activities that precede and follow them.

These activities are used to draw a PERT

diagram, which consists of a network of:

Arrowsrepresenting activities that require

time and resources. Nodesrepresenting completion and initiation

of activities.


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The critical path in a PERT diagram is the

path requiring the greatest amount of time.

If an activity on the critical path is delayed,

the whole project is delayed.

Resources may be shifted to the critical

path to reduce the delay.


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Design

Birdhouse

(2)

(Bill)

Buy Wood

& Nails

(1)(Bill)

Buy

Paint

(1)

(Sara)

Build

Base

(2)(Bill)

Build

Roof

(1)

(Bill)

Nail

Together

(2)

(Bill)

Paint &

Decorate

(3)

(Sara)

Sell

(2)

(Sara)

SAMPLE PERT CHART For building and selling a birdhouse.

Each block contains a task and a time estimate (may

include best time, worst time, and average time) May indicate who will be responsible for the task.


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Planning Techniques


monitor systems development activities

are:

Program Evaluation and Review Technique

(PERT)

Gantt Charts


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A Gantt chart is a bar chart with project activities

on the left and time across the top.

For each activity, a bar of expected time is

drawn. As activities are completed, the bar is filled in.

The Gantt chart makes it easy to eyeball the

chart and understand the current status of a

project.

But the chart does not show the relationship

between activities like the PERT chart does.


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SAMPLE GANTT CHART

1 2 3 4 5 6 7 8 9 10

Design birdhouse

Buy wood & nails

Buy paint

Build roofBuild base

Nail together

Paint & decorate

Sell

Period

Complete

Testing

In Development

Milestone


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Explain why system changes triggerbehavioral reactions.


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BEHAVIORAL ASPECTS OF CHANGE

The best system will fail without the

support of the people it serves.

So the behavioral aspects of change are

crucial.

You need to be aware of and sensitive to

the types of behavioral problems that can

result from change.


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Why Behavioral Problems Occur

Employees will tend to view change as good if

they believe it will affect them positively and

vice versa.


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To minimize adverse behavioral reactions,

it helps to understand why resistance

occurs:

Personal characteristics and background Manner in which change is introduced

The rationale used to sell the system may need to vary

with the job responsibilities of the employees involved.


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occurs:


Experience with prior changes Fool me once, shame on me . . .

Lets see if I even give you asecond chance.


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occurs:


Experience with prior changes

Top management support


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occurs:




Communication


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occurs:




Communication Biases and natural resistance to change

Disruptive nature of the change process

Disturbances often create

negative feelings.


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To minimize adverse behavioral reactions,it helps to understand why resistanceoccurs:

Personal characteristics and background Manner in which change is introduced Experience with prior changes Top management support Communication Biases and natural resistance to change Disruptive nature of the change process Fear

May include fear of:

The unknown

Failure

Technology

Losing respect or status

Losing their jobs


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How People Resist AIS Changes

Resistance to change often takes one of

three forms:

Aggression

Behavior intended to destroy, cripple, or weaken the

systems effectiveness.

Examples: Increased error rates, disruptions, or

deliberate sabotage.


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three forms:

Aggression

Projection

Blaming the new system for any and every unpleasant

occurrence, i.e., the system becomes a scapegoat. To preserve the integrity of the system, these criticisms

must be controlled or answered.


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three forms:

Aggression

Projection

Avoidance

If I dont use this thing, maybe it will go away!


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Reactions to change can be improved by

observing the following guidelines:

Meet users needs with respect to the form,

content, and volume of system output. Keep communication lines open. Managers

and users should be fully informed about:

What changes are being made

Why

How it will benefit them

Who to contact with questions


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Maintain a safe and open atmosphere.

If employees become hostile, its an uphill battle

you probably wont win.

Obtain management support.Allay fears.

To the extent possible, reassure employees that

no major job losses or responsibility shifts will

occur. If employees are terminated, severance pay and

outplacement services should be provided.


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BEHAVIORAL ASPECTS OF CHANGEIS

Solicit user participation.

It is ego enhancing, challenging, and intrinsically

satisfying.

Users who participate will be more committed to

using the system.

Provide honest feedback.

Explain which suggestions are and are not being

used and why. Make sure users understand the system.

Dont underestimate training needs.


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Humanize the system. Employees shouldnt feel the computer is

controlling them or has usurped their positions.

Describe new challenges and opportunities. The system can provide greater job satisfaction

and increased opportunities.

Reexamine performance evaluation. Are performance standards and criteria realistic in

light of the change?

Test the systems integrity. It important to minimize bad impressions


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Avoid emotionalism.

Emotional issues should be allowed to cool, handled in

a non-confrontational manner, or sidestepped.

Present the system in the proper context.

Address the concerns of the people to whom youre

speaking, not the concerns of management or

developers.

Control the users expectations

Dont oversell, and be realistic.

Keep the system simple

Avoid complex systems that cause radical changes.


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Ignoring the preceding steps can leave to

behavior issues that are difficult or

impossible to reverse.


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Learning Objectives

1. Discuss the system analysis process and the activitiesin this phase

2. Discuss the conceptual systems design process and

the activities in this phase.

3. Discuss the physical systems design process and theactivities in this phase.

4. Discuss the systems implementation and conversion

processand the activities in this phase.

5. Discuss the systems operation and maintenanceprocess and the activities in this phase.


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Discuss the system analysis process and

the activities in this phase


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SYSTEMS ANALYSIS

When a new or improved system is

needed, a written request for systems

development is prepared. That request

describes: The current systems problems

The reasons for the proposed changes

The goals and objectives of a proposedsystem

The anticipated benefits and costs


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SYSTEMS ANALYSIS

The project development team will conduct

the systems analysis in five steps:

Initial investigation

Systems survey

Feasibility study

Information needs and systems requirements

Systems analysis report


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SYSTEMS ANALYSIS

The project development team will conduct

the systems analysis in five steps


Systems survey

Feasibility study




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SYSTEMS ANALYSIS

The initial investigation is conducted to:

Gain a clear picture of the problem or

need.

Sometimes what is thought to be the cause of theproblem is not the real source.


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SYSTEMS ANALYSIS


Gain a clear picture of the problem or need.

Determine the viability of the project and

expected costs and payoffs.


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SYSTEMS ANALYSIS




expected costs and payoffs. Evaluate the scope and nature of the new

AIS.

A new AIS is useful when problems are a result of:

Lack of information

Inaccessibility of data

Inefficient data processing

A new AIS will not answer problems such as:

A manager who has too many subordinates

A manager who lacks organizational skills

Failure to enforce existing problems


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SYSTEMS ANALYSIS




expected costs and payoffs. Evaluate the scope and nature of the new

AIS.

Recommend whether to proceed.

Either: Initiate the project as proposed.

Modify it.

Abandon it.


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SYSTEMS ANALYSIS

If the project is approved:

A proposal to conduct systems analysis is

prepared.

The project is assigned a priority and addedto the master plan.

The development team begins a survey of the

existing AIS.

The proposal will be modified as more

information becomes available.


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SYSTEMS ANALYSIS

The project development team will conductthe systems analysis in five steps


Systems survey

Feasibility study




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SYSTEMS ANALYSIS

A systems survey involves an extensive study of thecurrent AIS which could take weeks or months.Objectives are: Gain a thorough understanding of:

Company operations, policies, and procedures

Data and information flow

AIS strengths and weaknesses

Available hardware, software, and personnel

Make preliminary assessments of current and future

processing needs, and determine extent and nature ofneeded changes.

Develop working relationships with users and build support.

Collect data that identify user needs, conduct a feasibilityanalysis, and make recommendations to management.


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SYSTEMS ANALYSIS

Data can be gathered from:

Employees.

Documentation such as organization charts

and procedure manuals. External sources such as:

Consultants

Customers

Suppliers

Industry associations

Government agencies


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SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Once the data is gathered, documentfindings and model the existing system.

Documentation consists of:

Questionnaire copies Interview notes

Memos

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Another form of documentation is asystem model:

Physical modelsillustrate how a systemfunctions by describing: Flow of documents.

Computer processes performed and the peopledoing them.

Equipment used.

Any other physical elements.

Logical modelsillustrate what is being doneregardless of how the flow is accomplished.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

At the end of this phase, prepare systemssurvey report:

Outlines and documents the data gathered.

Provides recommendations that result fromthe systems survey.


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SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

After the systems survey, a more thoroughfeasibility analysis is conducted.

This analysis is updated regularly as the

project proceeds and costs and benefitsbecome clearer.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



Systems survey

Feasibility study

Information needs and systems

requirements Systems analysis report

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Once a project clears the feasibility hurdle, the companyidentifies the information needs of AIS users and

documents systems processes, including:

- Processes

Describes what is to be doneand by whom.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes

- Data elements

Describes name, size, format,

source, and significance of

necessary data elements.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes

- Data elements- Data structure A preliminary structure showing

how the data elements will be

organized into logical records.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes

- Data elements- Data structure

- Outputs Layouts of system outputs and a

description of their purpose,

frequency, and distribution.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes


- Outputs

- Inputs A copy of system inputs and a

description of their contents,

source, and who is responsiblefor them.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes


- Outputs

- Inputs

- Constraints

A description of deadlines,

schedules, security requirements,

staffing limitations, and legalrequirements.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes


- Outputs

- Inputs

- Constraints

- Controls Controls that are needed to

ensure accuracy and reliability.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



- Processes


- Outputs

- Inputs

- Documentation constraints

- Controls

- Reorganizations Changes in staffing, job

functions, etc., that would be

necessary.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Issues: There is much to be specified, even for a

simple AIS.

It may be difficult to get employees toaccurately articulate their needs.

Errors are best caught early, as the cost to

correct them increases significantly the farther

you are into the project.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Systems Objectives and Constraints Many entities take a systems app roachto

determining information needs and systems

requirements. Problems and alternatives are viewed from

the standpoint of the entire organizationas

opposed to a single department.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Systems objectives must be identified, soanalysts and users can focus on those elements

most vital to success of the AIS. These may

include:

- Usefulness

Able to help users make

decisions.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

Benefits exceed costs.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability

Data is processed accuratelyand reliably.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability

- Availability You can access it when you

need it.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability

- Availability- Timeliness

More critical information is

provided first.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

Efficient and courteous.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

- Capacity

Can handle peak periods.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

- Capacity

- Ease of use

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

- Capacity

- Ease of use

- Flexibility

Can accommodate changes.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

- Capacity

- Ease of use

- Flexibility

- Tractability Easily understood.

Facilitates problem solving and

future development.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

- Capacity

- Ease of use

- Flexibility

- Tractability- Auditability

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



include:

- Usefulness

- Economy

- Reliability


- Customer service

- Capacity

- Ease of use

- Flexibility

- Tractability- Auditability

- Security Available only toauthorized users.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

There are often trade-offs between objectives.

Organizational constraints make it impossible to

develop all parts of an AIS simultaneously.

You divide it into modules that are analyzed,developed, and installed independently.

When changes are made, only the affected modules

need to be changed.

The modules should be properly integrated into aworkable system.


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SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Strategies for DeterminingRequirements:

One or more of the following four strategies

are used to determine AIS requirements: Ask users what they need

This is the simplest and fastest strategy.

But many people dont realize or understand their true

needs. Its sometimes better to ask them what decisions they

make and what processes they are involved in.

Users also need to think beyond their current

information needs.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS




Analyze existing systems

Internal and external systems should be analyzed to

avoid reinventing the wheel.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS





Examine existing system use

Certain modules:

May not be used as intended

May be augmented by manual tasks

May be avoided altogether

Helps determine whether the system really needs to be

simply modified rather than replaced.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS





Examine existing system use

Create a prototype

Entails roughing out a system for users to critique. When they see something on a screen, its easier to

identify what they like and dont like.

Goes through iterations of improving and reviewing

with users until users agree on their needs.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Documentation and Approval of UserRequirements:

Detailed requirements for the new AIS shouldbe created and documented. How to produce the required features is

determined during the design phases of the SDLC.

The requirements list should be supported bysample input and output forms and charts that

make it easier to conceptualize. A nontechnical summary is often prepared for

management.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS

Once user requirements have beendetermined and documented, the project

team:

Meets with users. Explains the requirements.

Obtains their agreement and approval.

When an agreement is reached, usermanagement should sign off on the

requirements.

SYSTEMS ANALYSIS


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SYSTEMS ANALYSIS



Systems survey Feasibility study




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g j

Discuss the conceptual design process

and the activities in this phase

CONCEPTUAL SYSTEMS DESIGN


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In the conceptual sys tems designphase, a general framework is created forimplementing user requirements andsolving the problems identified in theanalysis phase.

The three main steps are: Evaluate design alternatives.

Prepare design specifications. Prepare the conceptual systems design

report.

Systems

AnalysisConceptual

Systems


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Prepare

Design

Specifications

PhysicalDesign

Implementation

And

Conversion

Operation

And

Maintenance

Prepare

Conceptual Systems

Design report

Evaluate

Design

Alternatives

Systems

Design

Systems

Analysis


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Prepare

Design

Specifications

PhysicalDesign

Implementation

And

Conversion

Operation

And

Maintenance

Prepare

Conceptual Systems

Design report

Evaluate

Design

Alternatives



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Evaluating Design Alternatives There are many design decisions that must

be made. For example:

Should a document be hard-copy or sent by EDI? Should the company use a large centralized

mainframe or some form of distributed processing?

What form should data entry take, e.g., keyboard,

optical character recognition, POS devices?



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Also, there are many ways to approach thesystems development process:

Packaged software

In-house development

End-user development

Outsourcing

The company also chooses between:

Modifying or enhancing existing software Replacing existing software

Reengineering its business processes



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The design team should identify a variety ofdesign alternatives and evaluate each withrespect to: How well it meets organizational and system

objectives

How well it meets user needs Whether it is economically feasible

Its advantages and disadvantages

The steering committee evaluates the

alternatives.

CONCEPTUAL DESIGN

CONSIDERATIONS AND ALTERNATIVES


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How should the communications channel beconfigured?

What type of communications channelshould be used?

Phone lines

Coaxial cable Fiber optics

Microwave

Satellite

CONCEPTUAL DESIGN



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What type of communications channel should beused?

What type of communications networkshould be used? Centralized

Decentralized

Distributed

Local area

CONCEPTUAL DESIGN



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What type of communications network should beused?

What type of storage media should be usedfor data? Tape

Disk

Diskette

Hard drive

CD

Paper

CONCEPTUAL DESIGN



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What type of storage media should be used fordata?

What type of data storage structure shouldbe used?

Files

Database

CONCEPTUAL DESIGN



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What type of storage media should be used fordata?

What type of data storage structure should beused?

How should files be organized andaccessed?

Random

Sequential

Indexed-sequential access

CONCEPTUAL DESIGN



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What media should be used to input data? Keying

OCR

MICR

POS EDI

Voice


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CONCEPTUAL DESIGN



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What media should be used to input data? What format will the input take?

How will the system be operated? In-house Outsourcing

CONCEPTUAL DESIGN



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How will the system be operated?

How frequently will outputs be produced?

Instantly Hourly

Daily

Weekly

Monthly

CONCEPTUAL DESIGN



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What media will be used for output? Paper

Screen

Voice

Diskette CD

Microfilm


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CONCEPTUAL DESIGN



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What media will be used for output? How will output be scheduled?

What format will the output take?

Narrative

Table

Graph

Electronic file or communication


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CONCEPTUAL DESIGN



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What form will printed output take?

What processing mode will be used? Manual

Batch

Real time

CONCEPTUAL DESIGN



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What processing mode will be used? What type of processor will be utilized?

Personal computer

Minicomputer

Mainframe

CONCEPTUAL DESIGN



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What processing mode will be used? What type of processor will be utilized?

How will software be acquired?

Canned

Custom

Modified

CONCEPTUAL DESIGN



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How will transactions be processed? By batch

Online

CONCEPTUAL DESIGN



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How will transactions be processed? How frequently will updates occur?

Instantly

Hourly

Daily

Weekly

Monthly

Systems

Analysis


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y

Prepare

Design

Specifications

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance

Prepare

Conceptual Systems

Design report

Evaluate

Design

Alternatives



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Prepare design specifications Once a design has been selected, the

project team develops the conceptual

design speci f icat ionsfor the followingelements:

Output

Because output is what goes to the user and thesystem must be designed to meet user needs, the

output specifications are prepared first.



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Output

Data storage How will data be stored to produce the desired

outputs?



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Output

Data storage Input

What types of data must be entered to produce the

desired outputs?



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Output

Data storage

Input Processing procedures and operations

How will data be processed and in what sequence

to produce the desired outputs?

Systems

Analysis


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Prepare

Design

Specifications

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance

Prepare

Conceptual Systems

Design report

Evaluate

Design

Alternatives



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Prepare the Conceptual SystemsDesign Report

A conceptual systems design reportis

prepared at the end of the conceptual designphase to:

Guide physical system design activities.

Communicate how management and user

information needs will be met. Help the steering committee assess system

feasibility.



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The main component is a description of one ormore recommended system designs. This

description contains:

The contents of each output, database, and input.

Processing flows and the relationships among

programs, files, inputs, and outputs.

Hardware, software, and resource requirements.

Audit, control, and security processes and

procedures.

A discussion of assumptions or unresolved problems

that might affect the final design.



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Discuss the physical system design

process and the activities in this phase

PHYSICAL SYSTEMS DESIGN


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During the physical systems design phase, thecompany determines how the conceptual AISdesign is to be implemented. The broad, user-oriented requirements of conceptual

design are translated into detailed specifications used

to code and test computer programs. Phases include:

Designing output

Creating files and databases

Designing input

Writing computer programs Developing procedures

Building in controls

Systems

Analysis


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Conceptual

Systems

Design

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

duresDesign

Controls

Design

PhysicalSystems

Design

Systems

Analysis


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Conceptual

Systems

Design

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

duresDesign

Controls

Design



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Output Design The objective of output design is to

determine the nature, format, content,

and timing of printed reports,documents, and screen displays.

Requires cooperation between users and

designers.



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Important design considerations include: Use of the output

Who will use it and why?

When is it needed?

What decisions will it facilitate?


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Output medium

Output format Should select the format thatclearly conveys the mostinformation.

Could be:

Table

Narrative

Graphic



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Output medium

Output format Pre-printed Should paper output be on

preprinted form and/or

turnaround document?



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Output medium

Output format Pre-printed

Location Where is the output to besent?



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Output medium


Location

Access Who should be able to

access hard-copy andscreen output?



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Output medium


Location

Access Detail

Lengthy output should be preceded by an

executive summary and a table of contents.

Headings and legends organize data and

highlight important items.

Detailed info goes in an appendix.



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Output medium


Location

Access Detail

Timeliness

How often should the output be produced?



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Outputs usually fit into one of the followingfour categories:

Scheduled reports

Have pre-specified content and format.

Are prepared on a regular basis.

Examples:

Weekly sales analysis

Monthly financial statements


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Scheduled reports

Special-purpose analysis reports Triggered exception reports


Prepared only in response to abnormal

conditions, i.e., the trigger.

Example:

Cost overruns



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Scheduled reports

Special-purpose analysis reports Triggered exception reports

Demand reports


Prepared only on request.


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Systems

Analysis


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Conceptual

Systems

Design

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

duresDesign

Controls

Design



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File and Database Design Various company segments need to store data in

compatible formats so that data can be shared across

units.

Important file and database design considerationsinclude:

Storage medium Hard drive

Disk

Diskette

CD Tape

Paper



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units.


Storage medium

Processing mode Manual

Batch

Real time



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units.


Storage medium

Processing mode

Maintenance What procedures are needed to

effectively maintain the data?



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units.


Storage medium

Processing mode

Maintenance

Size How many records and how big are they?

How fast are they expected to grow?



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units.


Storage medium

Processing mode

Maintenance

Size

Activity level

What portion of records are added or

deleted each year?

What portion needs to be updated?

Systems

Analysis


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Conceptual

SystemsDesign

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

duresDesign

Controls

Design



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Input Design Systems designers must identify the

different types of data input and optimal

input methods. There are two principal types of data

input:

Forms Computer screens



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Considerations in input design include: Input medium Keyboard

OCR

MICR

POS terminal EDI

Voice input



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Considerations in input design include: Input medium

Input source

Where do data originate?

Computer

Customer

Remote location



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Input source

Input format What format captures the data with

the least effort or cost? Source or turnaround document

Screen

Source data automation



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Input source

Input format

Input type What is the nature of the data?



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Input source

Input format

Input type

Volume How much data are to be entered?



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Input source

Input format

Input type

Volume

Personnel

What functions and expertise do the data

entry operators have?

Is additional training necessary?



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Input source

Input format

Input type

Volume

Personnel

Frequency How often is data to be entered?



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Input source

Input format

Input type

Volume

Personnel

Frequency

Cost

How can costs be minimized without

adversely affecting efficiency andaccuracy?



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Input source

Input format

Input type

Volume

Personnel

Frequency

Cost

Error detection and correction

What errors are possible?

How can they be detected and corrected?


Preprint as much data as possible.

Use appropriate weight and grade of paper.

Use bold type, double-thick lines, and shading to


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Forms DesignAlthough input is evolving toward source data

automation, forms design is still important.

Following are important principles for

designing new forms and evaluating existing

ones:

General considerations

Use bold type, double thick lines, and shading to

highlight different parts of the form. Use a standard size and one that is consistent with

requirements for filing, binding, or mailing.

If mailed to external parties, position the address for

placement in a window envelope.

Have copies of the form printed in different colors tofacilitate accurate distribution.

Include clear instructions for completing the form.



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ones:


Introductory section of form

Place the form name at the top in bold type.

Have the forms pre-numberedconsecutively.

If distributed to external parties, have

company name and address pre-printed on

the form.



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ones:


Introductory section of form Main body of form

Group together logically related information

(e.g., info about the customer, info about

the product).

Provide sufficient room to record each item.

Order the data items consistent with thesequence in which the data is likely to be

gathered.

Use codes and check-offs in places where

standardized explanations are likely.



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ones:


Introductory section of form Main body of form

Conclusion section of form

Provide space for:

Recording final disposition of the form.

Approval signatures.

Dates of approval and final disposition.

A dollar or numeric total.

Clearly indicate the distribution ofeach form.


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Computer screens are most effective when the followingprinciples are used:

Organize the screen for quick, accurate, and complete entry

of the data.

Minimize input by retrieving as much as possible from

the system.

Example: If the customer number is entered, retrieve his

name/address data from the system.



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Organize the screen for quick, accurate, and complete entry of

the data.

Enter data in the same order it appears on the document.



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the data.


Complete the screen from left to right and top to bottom,grouping logically related data together.



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the data.



Design the screen so users can jump from one data entry

location to another or use a single key to go directly to

screen locations.



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the data.




location to another or use a single key to go directly to screen

locations.

Make it easy to correct mistakes.

Use clear and explicit error messages that are consistent

on all screens.

Provide a help feature for online assistance.



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the data.




location to another or use a single key to go directly to screen

locations.

Make it easy to correct mistakes.

Avoid clutter by restricting the amount of data on one

screen.

Limit the number of menu options on a single screen.

Systems

Analysis

C t l


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Conceptual

SystemsDesign

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

dures

Design

Controls

Design



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Program Design Program development is one of the most time-

consuming activities in the SDLC.

A struc tured prog ramm ingprocess should be

followed: With structured programming, programs should be

subdivided into small, well-defined modules to reduce

complexity and enhance reliability and modifiability.

Modules should interact with a control module rather than

with each other. To facilitate testing and modification, each module should

have only one entry and exit point.



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To improve software quality, organizationsshould develop programming standards (rules

for writing programs).

Contributes to consistency among programs.

Makes them easier to read and maintain.

Consider doing structured program walk-

throughs to find incorrect logic, errors,

omissions, or other problems.



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Program preparation time may range from a fewdays to a few years, depending on complexity.

Though accountants need not be programmers,

they should understand how software is created.

The following slides discuss the eight steps fordeveloping software and where these steps take

place in the SDLC.


Systems


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STEP ONE: Determine userneeds.

Occurs during the systems analysis

stage of the SDLC.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


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Systems


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STEP THREE: Write the programcode.

Design in increasing levels of detail,

known as hierarchical prog ram

design. Begun during systems design and

completed during systems

implementation.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


STEP FOUR T t th dSystems


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STEP FOUR: Test the program code.

Debuggingis discovering and

eliminating program errors.

Desk checkinghappens after a

program is coded and involves a

visual and mental review to discover

programming errors.

Programs are tested for logic errors

using test data that simulates both

valid transactions and all possible

error conditions.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


Systems


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Large programs are often testedin three stages:

Individual program modules.

The linkages between the module

and the control module. The interfaces between the

program being tested and other

application programs.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


Systems


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Errors need to be found as soonas possible in the development

process.

Errors discovered late cost 80-

1000% more to fix than thosefound early.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


Systems


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STEP FIVE: Document theprogram.

Documentation explains how

programs work and helps

correct and resolve errors. Includes flowcharts, record

layouts, E-R diagrams, REA

data models, narrative

descriptions of the system, etc.,

organized in a manual.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


Systems


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STEP SIX: Train program users. Often uses the program

documentation.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


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STEP SEVEN: Install the system.-All components are brought

together, and the company

begins to use the system.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance


Systems


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STEP EIGHT: Use andmodify the system.

Program maintenanceis aresponse to any factors that

require program revision. Includes requests for:

New or revised reports.

Changes in input, file content, or

values such as tax rates. Error detection and correction.

Conversion to new hardware.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

And

Conversion

Operation

And

Maintenance

Systems

Analysis

Conceptual


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Conceptual

SystemsDesign

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

dures

Design

Controls

Design


Procedures Design


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Procedures Design

Individuals who interact with a newly-designed AIS need procedures to cover: Input preparation

Transaction processing Error detection and correction

Controls

Reconciliation of balances

Database access Output preparation and distribution

Computer operator instructions



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Procedures may take the form of: System manuals

User instruction classes

Training materials

Online help screens


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Systems

Analysis

Conceptual


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p

SystemsDesign

Output

Design

Implementation

And

Conversion

Operation

And

Maintenance

File & DB

Design

Input

Design

Program

Design

Proce-

dures

Design

Controls

Design



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Controls Design Improperly controlled input, processing, anddatabase functions produce information ofquestionable value.

Controls must be built into an AIS to ensureits effectiveness, efficiency, and accuracy.These controls should: Minimize errors

Detect and correct errors when they do occurAccountants play a vital role in this area.



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Important control concerns that must beaddressed include:

Validity Are all interactions valid?



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Validity

Authorization

Are input, processing, storage, and

output activities authorized by the

appropriate managers?



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Validity

Authorization

Accuracy Is input verified to ensure accuracy? What controls ensure that data is not

lost when passing between processing

activities?



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Validity

Authorization

Accuracy Security

Is the system protected against:

Unauthorized physical and logical access to prevent

improper use, alteration, destruction, or disclosure ofinformation and software?

Theft of system resources?



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Validity

Authorization

Accuracy Security

Numerical control

Are documents pre-numbered to prevent errors or

intentional misuse and to detect when documents aremissing or stolen?



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Validity

Authorization

Accuracy Security

Numerical control

Availability

Is the system available as set forth in agreements?

Can users enter, update, and retrieve data during those

times?



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Validity

Authorization

Accuracy Security

Numerical control

Availability

Maintainability

Can the system be modified without affecting system

availability, security, and integrity?

Are only authorized, tested, and documented changesmade to the system and data?

ppt_03_System Dev.pdf

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Transcript of ppt_03_System Dev.pdf