romney_ch20.ppt

C

HAPTER 20

Systems Design,

Implementation, and

INTRODUCTION

• Questions to be addressed in this chapter

include:

– What are the activities that take place in the

conceptual design phase of the systems development

life cycle (SDLC)?

– What activities take place in the physical systems

design phase?

– What happens during the systems implementation

and conversion process?

INTRODUCTION

• Accountants must understand the entire systems

development process, because they are

involved in several ways:

– Helping to specify their needs.

– As members of the development team.

– As auditors after the fact.

• Accountants also help keep the project on track

by:

– Evaluating and measuring benefits.

– Measuring costs.

INTRODUCTION

• Effective systems analysis and design

can ensure that developers:

INTRODUCTION

• The crucial phases of the SDLC include:

– Systems analysis to define the new systems

requirements (discussed in Chapter 18).

– The phases discussed in this chapter, which

include:

• Conceptual systems design

• Physical systems design

INTRODUCTION

• The crucial phases of the SDLC include:

– Systems analysis to define the new systems

requirements (discussed in Chapter 18).

– The phases discussed in this chapter, which

include:

•

Conceptual systems design

• Physical systems design

CONCEPTUAL SYSTEMS DESIGN

• In the

conceptual systems design

phase, a general framework is created for

implementing user requirements and

solving the problems identified in the

analysis phase.

• The three main steps are:

– Evaluate design alternatives.

– Prepare design specifications.

CONCEPTUAL SYSTEMS DESIGN

•

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,

CONCEPTUAL SYSTEMS DESIGN

• Also, there are many ways to approach the

systems development process:

– Packaged software

– In-house development

– End-user development

– Outsourcing

• The company also chooses between:

– Modifying or enhancing existing software

– Replacing existing software

CONCEPTUAL SYSTEMS DESIGN

• The design team should identify a variety of

design alternatives and evaluate each with

respect 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.

•

_{Click here}

_{to view some of the design}

CONCEPTUAL SYSTEMS DESIGN

•

_{Prepare design specifications}

– Once a design has been selected, the

project team develops the

conceptual

design specifications

for the following

elements:

•

Output

CONCEPTUAL SYSTEMS DESIGN

•

_{Prepare design specifications}

– Once a design has been selected, the

project team develops the

conceptual

design specifications

for the following

elements:

• Output

•

Data storage

CONCEPTUAL SYSTEMS DESIGN

•

_{Prepare design specifications}

– Once a design has been selected, the

project team develops the

conceptual

design specifications

for the following

elements:

• Output

• Data storage

•

_Input

CONCEPTUAL SYSTEMS DESIGN

•

Prepare design specifications

– Once a design has been selected, the

project team develops the

conceptual

design specifications

for the following

elements:

• Output

• Data storage

• Input

•

Processing procedures and operations

Systems

Analysis

Prepare

Design

Specifications

Physical

Design

Implementation

and

Conversion

Operation

and

Prepare

Conceptual Systems

Design Report

CONCEPTUAL SYSTEMS DESIGN

•

Prepare the conceptual systems design

report

– A

conceptual systems design report

is

prepared at the end of the conceptual design

phase to:

• Guide physical system design activities.

• Communicate how management and user

information needs will be met.

CONCEPTUAL SYSTEMS DESIGN

• The main component is a description of one or

more 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.

INTRODUCTION

• The crucial phases of the SDLC include:

– Systems analysis to define the new systems

requirements (discussed in Chapter 18).

– The phases discussed in this chapter, which

include:

• Conceptual systems design

•

Physical systems design

PHYSICAL SYSTEMS DESIGN

• During the physical systems design phase, the

company determines how the conceptual AIS

design 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

Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

File and DB

PHYSICAL SYSTEMS DESIGN

•

_{Output design}

– The objective of output design is to

determine the nature, format, content,

and timing of printed reports,

documents, and screen displays.

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

–

Use of the output

•

Who will use it and why?

•

When is it needed?

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

–

Output medium

•

Paper

•

Screen

•

Voice response

•

Diskette

•

Microfilm

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

– Output medium

–

Output format

•

Should select the format that

clearly conveys the most

information.

•

Could be:

–

Table

–

Narrative

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

– Output medium

– Output format

–

_Pre-printed

•

Should paper output be on

preprinted form and/or

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

– Output medium

– Output format

– Pre-printed

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

– Output medium

– Output format

– Pre-printed

– Location

–

Access

•

Who should be able to

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

– Output medium

– Output format

– Pre-printed

– 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.

PHYSICAL SYSTEMS DESIGN

• Important design considerations include:

– Use of the output

– Output medium

– Output format

– Pre-printed

– Location

– Access

– Detail

–

_Timeliness

PHYSICAL SYSTEMS DESIGN

• Outputs usually fit into one of the following

four categories:

–

Scheduled reports

•

Have pre-specified content and format.

•

Are prepared on a regular basis.

•

Examples:

–

Weekly sales analysis

PHYSICAL SYSTEMS DESIGN

• Outputs usually fit into one of the following

four categories:

– Scheduled reports

–

Special-purpose analysis reports

•

No pre-specified content and format.

•

Typically prepared in response to a

management request.

•

Example:

PHYSICAL SYSTEMS DESIGN

• Outputs usually fit into one of the following

four categories:

– Scheduled reports

– Special-purpose analysis reports

–

_{Triggered exception reports}

•

Have pre-specified content and format.

•

Prepared only in response to abnormal

conditions, i.e., the “trigger.”

PHYSICAL SYSTEMS DESIGN

• Outputs usually fit into one of the following

four categories:

– Scheduled reports

– Special-purpose analysis reports

– Triggered exception reports

–

Demand reports

•

Have pre-specified content and format.

PHYSICAL SYSTEMS DESIGN

• AIS developers prepare sample outputs

and users evaluate them to ensure they

are complete, relevant, and useful.

– Modifications are made as needed to ensure

acceptability.

– Many organizations require users to sign off

on these documents before proceeding

Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

PHYSICAL SYSTEMS DESIGN

•

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 considerations

include:

•

Storage medium

•

_•

Hard drive

_Disk

•

Diskette

•

CD

•

Tape

PHYSICAL SYSTEMS DESIGN

•

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 considerations

include:

• Storage medium

•

Processing mode

•

_•

Manual

_Batch

PHYSICAL SYSTEMS DESIGN

•

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 considerations

include:

• Storage medium

• Processing mode

•

Maintenance

_•

_{What procedures are needed to}

PHYSICAL SYSTEMS DESIGN

•

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 considerations

include:

• Storage medium

• Processing mode

• Maintenance

•

Size

•

How many records and how big are they?

PHYSICAL SYSTEMS DESIGN

•

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 considerations

include:

• Storage medium

• Processing mode

• Maintenance

• Size

•

Activity level

•

What portion of records are added or

deleted each year?

Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

PHYSICAL SYSTEMS DESIGN

•

_{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

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

–

Input medium

•

Keyboard

•

OCR

•

MICR

•

POS terminal

•

EDI

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

–

Input source

•

Where do data originate?

–

Computer

–

Customer

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

–

Input format

•

What format captures the data with

the least effort or cost?

–

Source or turnaround document

–

Screen

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

– Input format

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

– Input format

– Input type

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

– Input format

– Input type

– Volume

–

Personnel

•

What functions and expertise do the data

entry operators have?

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

– Input format

– Input type

– Volume

– Personnel

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

– Input format

– Input type

– Volume

– Personnel

– Frequency

–

Cost

PHYSICAL SYSTEMS DESIGN

•

Considerations in input design include:

– Input medium

– Input source

– Input format

– Input type

– Volume

– Personnel

– Frequency

– Cost

–

Error detection and correction

•

What errors are possible?

PHYSICAL SYSTEMS DESIGN

•

Forms design

– Although 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

•

Preprint as much data as possible.

•

Use appropriate weight and grade of paper.

•

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 to

facilitate accurate distribution.

PHYSICAL SYSTEMS DESIGN

•

Forms design

– Although 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

•

Introductory section of form

•

Place the form name at the top in bold type.

•

Have the forms pre-numbered

consecutively.

•

If distributed to external parties, have

PHYSICAL SYSTEMS DESIGN

•

Forms design

– Although 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

• 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 the

sequence in which the data is likely to be

gathered.

PHYSICAL SYSTEMS DESIGN

•

Forms Design

– Although 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

• 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.

PHYSICAL SYSTEMS DESIGN

•

Designing computer screens

– It is more efficient to enter data directly into

the computer than to record it on paper for

subsequent entry.

PHYSICAL SYSTEMS DESIGN

• Computer screens are most effective when the following

principles 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.

PHYSICAL SYSTEMS DESIGN

• Computer screens are most effective when the following

principles are used:

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

the data.

PHYSICAL SYSTEMS DESIGN

• Computer screens are most effective when the following

principles are used:

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

the data.

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

PHYSICAL SYSTEMS DESIGN

• Computer screens are most effective when the following

principles are used:

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

the data.

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

– Complete the screen from left to right and top to bottom,

grouping logically related data together.

PHYSICAL SYSTEMS DESIGN

• Computer screens are most effective when the following

principles are used:

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

the data.

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

– Complete the screen from left to right and top to bottom,

grouping logically related data together.

– 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.

–

Make it easy to correct mistakes.

PHYSICAL SYSTEMS DESIGN

• Computer screens are most effective when the following

principles are used:

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

the data.

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

– Complete the screen from left to right and top to bottom,

grouping logically related data together.

– 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.

– Make it easy to correct mistakes.

–

Avoid clutter by restricting the amount of data on one

screen.

Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

PHYSICAL SYSTEMS DESIGN

•

Program design

– Program development is one of the most

time-consuming activities in the SDLC.

– A

structured programming

process 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.

PHYSICAL SYSTEMS DESIGN

• To improve software quality, organizations

should develop programming standards (rules

for writing programs).

– Contributes to consistency among programs.

– Makes them easier to read and maintain.

PHYSICAL SYSTEMS DESIGN

• Program preparation time may range from a few

days 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 for

PHYSICAL SYSTEMS DESIGN

• STEP ONE: Determine user

needs.

– Occurs during the systems analysis

stage of the SDLC.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

PHYSICAL SYSTEMS DESIGN

• STEP TWO: Develop and

document a plan.

– Occurs during the conceptual design

phase and the beginning of physical

design.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

PHYSICAL SYSTEMS DESIGN

• STEP THREE: Write the program

code.

– Design in increasing levels of detail,

known as

hierarchical program

design

.

– Begun during systems design and

completed during systems

PHYSICAL SYSTEMS DESIGN

• STEP FOUR: Test the program code.

–

Debugging

is discovering and

eliminating program errors.

–

Desk checking

happens after a

program is coded and involves a

visual and mental review to discover

programming errors.

PHYSICAL SYSTEMS DESIGN

– Large programs are often tested

in three stages:

• Individual program modules.

• The linkages between the module

and the control module.

• The interfaces between the

PHYSICAL SYSTEMS DESIGN

– Errors need to be found as soon

as possible in the development

process.

– Errors discovered late cost 80–

1000% more to fix than those

found early.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

PHYSICAL SYSTEMS DESIGN

• STEP FIVE: Document the

program.

– 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.

PHYSICAL SYSTEMS DESIGN

• STEP SIX: Train program users.

– Often uses the program

documentation.

Systems

Analysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

PHYSICAL SYSTEMS DESIGN

• 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

PHYSICAL SYSTEMS DESIGN

• STEP EIGHT: Use and modify

the system.

–

Program maintenance

is a

response 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

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

PHYSICAL SYSTEMS DESIGN

•

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

PHYSICAL SYSTEMS DESIGN

• Procedures may take the form of:

– System manuals

– User instruction classes

– Training materials

PHYSICAL SYSTEMS DESIGN

• The procedures may be written by:

– Development teams;

– Users; or

Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

PHYSICAL SYSTEMS DESIGN

•

Controls design

– Improperly controlled input, processing, and

database functions produce information of

questionable value.

– Controls must be built into an AIS to ensure

its effectiveness, efficiency, and accuracy.

These controls should:

• Minimize errors.

• Detect and correct errors when they do occur.

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

–

Authorization

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

– Authorization

–

Accuracy

•

Is input verified to ensure accuracy?

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

– Authorization

– Accuracy

–

Security

•

Is the system protected against:

–

Unauthorized physical and logical access to prevent

improper use, alteration, destruction, or disclosure of

information and software?

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

– Authorization

– Accuracy

– Security

–

Numerical control

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

– Authorization

– Accuracy

– Security

– Numerical control

–

Availability

•

Is the system available as set forth in agreements?

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– 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 changes

made to the system and data?

•

Are resources available to manage, schedule, document,

and communicate changes to management and

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

– Authorization

– Accuracy

– Security

– Numerical control

– Availability

– Maintainability

–

Integrity

•

Is processing complete, accurate, timely, and

authorized?

PHYSICAL SYSTEMS DESIGN

•

Important control concerns that must be

addressed include:

– Validity

– Authorization

– Accuracy

– Security

– Numerical control

– Availability

– Maintainability

– Integrity

–

Audit trail

PHYSICAL SYSTEMS DESIGN

•

Physical systems design report

– At the end of the physical design phase, a

physical systems design report

is prepared,

summarizing what was accomplished.

– This report serves as the basis for

INTRODUCTION

• The crucial phases of the SDLC include:

– Systems analysis to define the new systems

requirements (discussed in Chapter 18).

– The phases discussed in this chapter, which

include:

• Conceptual systems design

• Physical systems design

•

Systems implementation and conversion

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Systems implementation

–

Systems

implementation

is the process of

installing hardware and software and

getting the AIS up and running.

–

Phases include:

•

Developing a plan

•

Preparing the site

•

Installing and testing hardware and software

•

Selecting and training personnel

•

Completing documentation

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

and

Prepare Site;

Install and Test

Hardware

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

Prepare Site;

Install and Test

Hardware

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Implementation planning

–

An

implementation plan

consists of:

•

Implementation tasks

•

Expected completion dates

•

Cost estimates

•

Specification of the person(s) responsible for each task

–

The plan specifies when the project should be

complete and operational.

–

The implementation team should identify risk

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

AIS changes may require adjustments to the

company’s organizational structure,

including:

–

Creation of new departments.

–

Elimination or downsizing of existing

departments.

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

and

Prepare site;

Install and Test

hardware

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Site preparation

–

A large computer may require changes such as:

•

New electrical outlets

•

Data communications facilities

•

Raised floors

•

Humidity controls

•

Special lighting

•

Air-conditioning

•

Security measures, such as:

–

Fire protection

–

Emergency power supply

SYSTEMS IMPLEMENTATION AND

CONVERSION

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

Prepare Site;

Install and Test

Hardware

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

_{Select and train personnel}

– Employees can be hired from outside or

transferred internally.

• Hiring from within is usually more effective and

less costly, because the employees already

understand the business.

• Transferring displaced employees can enhance

loyalty and morale.

– Companies take training shortcuts because:

• Effective training is time-consuming and

expensive.

SYSTEMS IMPLEMENTATION AND

CONVERSION

• When training is insufficient, the company will

not achieve the expected return on investment.

• The hidden cost is that users will turn to their

coworkers who have mastered the system for

help. Results in:

– Less productive coworkers

– Increased costs

• Effective training includes:

– Hardware and software skills

– Orientation to new policies and operations

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Types of training include:

– Technical training from vendors

– Self-study manuals

– Computer-aided instruction

– Videotape presentations

– Role-playing

– Case studies

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

Prepare site;

Install and Test

Hardware

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three types of documentation must be

prepared for new systems:

–

Development documentation

•

Describes the AIS and includes:

–

A system description.

–

Copies of output, input, file, and database layouts.

–

Program flowcharts.

–

Test results.

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three types of documentation must be

prepared for new systems:

– Development documentation

–

Operations documentation

•

Includes:

–

Operating schedules.

–

Files and databases accessed.

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three types of documentation must be

prepared for new systems:

– Development documentation

– Operations documentation

–

User documentation

•

Teaches users how to operate the AIS.

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

Prepare site;

Install and Test

Hardware

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Test the system

– Inadequate system testing has contributed to the

failure of systems.

– All of the following should be given a trial run in

realistic circumstances.

• Documents and reports

• User input

• Operating and control procedures

• Processing procedures

• Computer programs

– Should also test:

• Capacity limits

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three common forms of testing include:

–

Walk-throughs

•

Step-by-step reviews of procedures or program logic.

–

Attended by the development team and users early in system

design.

–

Focus is on organization:

•

Input

•

Files

•

Outputs

•

Data flows

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three common forms of testing include:

– Walk-throughs

–

Processing test transactions

•

Determines whether the program operates as

designed.

•

Requires both valid and erroneous data.

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three common forms of testing include:

– Walk-throughs

– Processing test transactions

–

Acceptance tests

•

Uses copies of real transactions and files

rather than hypothetical ones.

–

Users develop acceptance criteria.

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Three common forms of testing include:

– Walk-throughs

– Processing test transactions

– Acceptance tests

•

Even software purchased from an

Systems

Analysis

Conceptual

Systems

Design

Physical

Systems

Design

Operation

Prepare site;

Install and test

hardware

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Systems conversion

–

Conversion

is the process of changing from the old

AIS to the new.

– Many elements must be converted, including:

• Hardware

• Software

• Data files

• Procedures

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Conversion approaches

– Four conversion approaches are used to

change from an old to a new system:

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Conversion approaches

– Four conversion approaches are used to

change from an old to a new system:

•

Direct conversion

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Direct conversion

– Immediately terminates the old AIS when the

new one is introduced.

– Appropriate when:

• The old AIS has no value; or

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Main advantage to direct conversion:

– It’s inexpensive

• Main disadvantage:

– It provides no backup AIS.

• There is a high risk of failure unless the

new system has been very carefully

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Conversion approaches

– Four conversion approaches are used to

change from an old to a new system:

• Direct conversion

•

Parallel conversion

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Parallel conversion

– Operates the old and new systems

simultaneously for a period of time.

– You can process transactions with both

systems, compare output, reconcile

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Main advantage to parallel conversion:

– It protects the company from errors.

• Main disadvantage:

– It is costly and stressful for employees to process all

transactions twice.

• Because companies often experience problems

during conversion, parallel processing has

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Conversion approaches

– Four conversion approaches are used to

change from an old to a new system:

• Direct conversion

• Parallel conversion

•

Phase-in conversion

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Phase-in conversion

– Gradually replaces elements of the old AIS with the

new one.

– The new system is often phased in a module at a

time.

– Main Advantage:

• Data processing resources can be acquired over time.

– Disadvantages:

• Costs of creating temporary interfaces between old and new

AIS.

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Conversion approaches

– Four conversion approaches are used to

change from an old to a new system:

• Direct conversion

• Parallel conversion

• Phase-in conversion

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

Pilot conversion

– Implements a system in just one part of the

organization, e.g., a branch office or a single store.

– When problems with the system are resolved, the

new system could be implemented at the remaining

locations.

– Advantages:

• Localizes conversion problems and allows training in a live

environment.

– Disadvantages:

• Long conversion time.

SYSTEMS IMPLEMENTATION AND

CONVERSION

•

_{Data conversion}

– Data conversion can be time-consuming,

tedious, and expense.

– The difficulty and magnitude is easy to

underestimate.

– Data files may need to be modified in three

ways:

• Files may be moved to a different storage medium

(e.g., tape to disk).

• Data content may be changed (e.g., fields added

or deleted).

SYSTEMS IMPLEMENTATION AND

CONVERSION

• Steps in the data conversion process:

– Decide which data files need to be converted.

– Check files for completeness and data inaccuracies,

and remove any inconsistencies.

– Do the actual data conversion.

– Validate the new files to ensure data were not lost

during conversion.

– If the file conversion is lengthy, update the new files

with transactions that occurred during data

conversion.

– After conversion and testing, monitor the system to

make sure it runs smoothly and accurately.

Systems

Analysis

Conceptual

Systems

Design

Physical

Design

Implementation

and

Conversion

Operation

and

OPERATIONS AND MAINTENANCE

• The last step in the SDLC is to operate

and maintain the new system.

• A

post-implementation review

should be

conducted to ensure the new AIS meets

OPERATIONS AND MAINTENANCE

• Factors and questions include:

–

_{Goals and objectives}

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Goals and objectives

–

Satisfaction

•

Are users satisfied?

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Goals and objectives

– Satisfaction

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Goals and objectives

– Satisfaction

– Benefits

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Goals and objectives

– Satisfaction

– Benefits

– Costs

–

Reliability

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Goals and objectives

– Satisfaction

– Benefits

– Costs

– Reliability

–

_Accuracy

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Goals and objectives

– Satisfaction

– Benefits

– Costs

– Reliability

– Accuracy

–

_Timeliness

OPERATIONS AND MAINTENANCE

• Factors and questions include:

–

_{Compatibility}

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Compatibility

–

Controls and security

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Compatibility

– Controls and security

–

Errors

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Compatibility

– Controls and security

– Errors

–

_Training

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Compatibility

– Controls and security

– Errors

– Training

–

Communications

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Compatibility

– Controls and security

– Errors

– Training

– Communications

–

_{Organization changes}

•

Are structural changes that resulted from the system

beneficial or harmful?

OPERATIONS AND MAINTENANCE

• Factors and questions include:

– Compatibility

– Controls and security

– Errors

– Training

– Communications

– Organization changes

–

_{Documentation}

OPERATIONS AND MAINTENANCE

• Any problems discovered during the

review should be brought to

management’s attention, and adjustments

should be made.

• When the review is complete, a

post-implementation review report

is

prepared.

OPERATIONS AND MAINTENANCE

• Control of the AIS is then passed to the

data processing department.

• But the work is not done.

– About 30% of the work takes place during

development.

SUMMARY AND CONCLUSIONS

• You’ve learned in more depth about the activities

that take place in the conceptual design phase of

the systems development life cycle (SDLC).

• You’ve also learned about activities that take

place in the physical systems design phase.

• You’ve explored what happens during the

systems implementation and conversion process.

• Finally, you’ve learned about the activities in the

last phase of the systems development life cycle

—the systems operation and maintenance