Ais Romney 2006 Slides 20 System Design

HAPTER 20 Systems Design, Implementation, and Operation

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?

What activities occur in the systems operation and maintenance process?

INTRODUCTION

Accountants must understand the entire systems development process, since 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.

Ensuring the project stays on schedule.

INTRODUCTION

Effective systems analysis and design can ensure that developers:

Correctly define the business problem.

Design the appropriate solution.

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

Operation and maintenance

INTRODUCTION

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.

Prepare the conceptual systems design report.

Systems Analysis Prepare Design Specifications Physical Design Implementation And Conversion Operation And Maintenance Prepare Conceptual Systems Design report Evaluate Design Alternatives Conceptual Systems Design

Systems Analysis Prepare Design Specifications Physical Design Implementation And Conversion Operation And Maintenance Prepare Conceptual Systems Design report Evaluate Design Alternatives

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?

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

Reengineering its business processes

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 considerations and alternatives from Table 20-1 in your textbook.

Design Considerations

CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES

How should the communications channel be configured?

Point-to-point

Multi-drop

Line-sharing

What type of communications channel should be used?

Phone lines

Coaxial cable

Fiber optics

Microwave

Satellite

What type of communications network should be used?

Centralized

Decentralized

Distributed

Local area

What type of storage media should be used for data?

Tape

Disk

Diskette

Hard drive

CD

Paper

What type of data storage structure should be used?

Files

Database

What type of data storage structure should be used?

How should files be organized and accessed?

Random

Sequential

Indexed-sequential access

What media should be used to input data?

Keying

OCR

MICR

POS

EDI

Voice

What format will the input take?

Source documents

Turnaround documents

Source data automation

Screen

How will the system be operated?

In-house

Outsourcing

How frequently will outputs be produced?

Instantly

Hourly

Daily

Weekly

Monthly

What media will be used for output?

Paper

Screen

Voice

Diskette

CD

Microfilm

How will output be scheduled?

On demand

At predetermined times

What format will the output take?

Narrative

Table

Graph

Electronic file or communication

What form will printed output take?

Pre-printed forms

Turnaround documents

System-generated forms

What processing mode will be used?

Manual

Batch

Real time

What type of processor will be utilized?

Personal computer

Minicomputer

Mainframe

What type of processor will be utilized?

How will software be acquired?

Canned

Custom

Modified

How will transactions be processed?

By batch

Online

How will transactions be processed?

How frequently will updates occur?

Instantly

Hourly

Daily

Weekly

Monthly

Prepare design specifications

Once a design has been selected, the project team develops the conceptual design specifications for the following elements:

Output

Because output is what goes to the user and the system must be designed to meet user needs, the output specifications are prepared first.

Output

Data storage

How will data be stored to produce the desired outputs?

Output

Data storage

Input

What types of data must be entered to produce the desired outputs?

Output

Data storage

Input

Processing procedures and operations

How will data be processed and in what sequence to produce the desired outputs?

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.

Help the steering committee assess system feasibility.

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.

A discussion of assumptions or unresolved problems that might affect the final design.

INTRODUCTION

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

Building in controls

Systems Analysis Conceptual Systems Design Output Design Implementation And Conversion Operation And Maintenance File & DB Design Input Design Program Design Proce- dures Design Controls Design Physical Systems Design

Systems Analysis Conceptual Systems Design Output Design Implementation And Conversion Operation And Maintenance File & DB Design Input Design Program Design Proce- dures Design Controls Design

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.

Important design considerations include:

Use of the output

Who will use it and why?

When is it needed?

What decisions will it facilitate?

Use of the output

Output medium

Paper

Screen

Voice response

Diskette

Microfilm

Other

Use of the output

Output medium

Output format

Should select the format that clearly conveys the most information.

Could be:

Table

Narrative

Graphic

Use of the output

Output medium

Output format

Pre-printed

Should paper output be on preprinted form and/or turnaround document?

Use of the output

Output medium

Output format

Pre-printed

Location

Where is the output to be sent?

Use of the output

Output medium

Output format

Pre-printed

Location

Access

Who should be able to access hard-copy and screen output?

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.

Detailed info goes in an appendix.

Use of the output

Output medium

Output format

Pre-printed

Location

Access

Detail

Timeliness

How often should the output be produced?

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

Monthly financial statements

Scheduled reports

Special-purpose analysis reports

No pre-specified content and format.

Typically prepared in response to a management request.

Example:

Analysis of impact of a government mandate on profitability

Scheduled reports

Triggered exception reports

Prepared only in response to abnormal conditions, i.e., the “trigger.”

Example:

Cost overruns

Scheduled reports

Triggered exception reports

Demand reports

Prepared only on request.

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 through the SDLC.

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

Paper

Storage medium

Processing mode

Manual

Batch

Real time

Storage medium

Processing mode

Maintenance

What procedures are needed to effectively maintain the data?

Storage medium

Processing mode

Maintenance

Size

How many records and how big are they?

How fast are they expected to grow?

Storage medium

Processing mode

Maintenance

Size

Activity level

What portion of records are added or deleted each year?

What portion needs to be updated?

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

Considerations in input design include:

Input medium

Keyboard

OCR

MICR

POS terminal

EDI

Voice input

Input medium

Input source

Where do data originate?

Computer

Customer

Remote location

Input medium

Input source

Input format

What format captures the data with the least effort or cost?

Source or turnaround document

Screen

Source data automation

Input medium

Input source

Input format

Input type

What is the nature of the data?

Input medium

Input source

Input format

Input type

Volume

How much data are to be entered?

Input medium

Input source

Input format

Input type

Volume

Personnel

What functions and expertise do the data entry operators have?

Is additional training necessary?

Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

How often is data to be entered?

Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

Cost

How can costs be minimized without adversely affecting efficiency and accuracy?

Input medium

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?

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.

Include clear instructions for completing the form.

Forms Design

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 company name and address pre-printed on the form.

Forms Design

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.

Use codes and check-offs in places where standardized explanations are likely.

Forms Design

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 of each form.

Designing Computer Screens

It is more efficient to enter data directly into the computer than to record it on paper for subsequent entry.

Therefore, it’s important to design computer screens for input as well as output.

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.

Example: If the customer number is entered, retrieve his name/address data from the system.

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

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.

Use clear and explicit error messages that are consistent on all screens.

Provide a help feature for online assistance.

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.

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.

To facilitate testing and modification, each module should have only one entry and exit point.

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.

Consider doing structured program walk-throughs to find incorrect logic, errors, omissions, or other problems.

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 developing software and where these steps take place in the SDLC.

STEP ONE: Determine user needs.

Occurs during the systems analysis stage of the SDLC.

Systems Analysis Conceptual Design Physical Design Implementation And Conversion Operation And Maintenance

STEP TWO: Develop and document a plan.

Occurs during the conceptual design phase and the beginning of physical 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 implementation.

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.

Programs are tested for logic errors using test data that simulates both valid transactions and all possible error conditions.

Large programs are often tested in 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.

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.

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.

STEP SIX: Train program users.

Often uses the program documentation.

STEP SEVEN: Install the system.

All components are brought together, and the company begins to use the system.

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.

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

Procedures may take the form of:

System manuals

User instruction classes

Training materials

Online help screens

The procedures may be written by:

Development teams;

Users; or

Teams representing both groups.

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

Accountants play a vital role in this area.

Important control concerns that must be addressed include:

Validity

Are all interactions valid?

Validity

Authorization

Are input, processing, storage, and output activities authorized by the appropriate managers?

Validity

Authorization

Accuracy

Is input verified to ensure accuracy?

What controls ensure that data is not lost when passing between processing activities?

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?

Theft of system resources?

Validity

Authorization

Accuracy

Security

Numerical control

Are documents pre-numbered to prevent errors or intentional misuse and to detect when documents are missing or stolen?

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?

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 authorized users?

Validity

Authorization

Accuracy

Security

Numerical control

Availability

Maintainability

Integrity

Is processing complete, accurate, timely, and authorized?

Is it free from unauthorized or inadvertent manipulations?

Validity

Authorization

Accuracy

Security

Numerical control

Availability

Maintainability

Integrity

Audit trail

Can data be traced from source to output and vice versa?

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 management’s decision whether to proceed to implementation.

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 management’s decision whether to proceed to implementation.

INTRODUCTION

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

Testing the system

Systems Analysis Conceptual Systems Design Physical Systems Design Operation And Maintenance Prepare site; Install & test hardware Select & Train Personnel System Implementation And Conversion Implementation Planning Complete documentation Test system Conversion

Systems Analysis Conceptual Systems Design Physical Systems Design Operation And Maintenance Prepare site; Install & test hardware Select & Train Personnel Implementation Planning Complete documentation Test system 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 factors that decrease the likelihood of successful implementation, and the plan should contain a strategy for coping with each of the risks.

AIS changes may require adjustments to the company’s organizational structure, including:

Creation of new departments.

Elimination or downsizing of existing departments.

Changes even in the data processing department.

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

Space for equipment, storage, and offices

Site preparation is a lengthy process and should begin well ahead of the installation date.

Select and Train Personnel

Employees can be hired from outside or transferred internally.

Hiring 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.

Those who understand the system are maintaining and upgrading it.

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

The training should be scheduled just before systems testing and conversion.

Types of training include:

Technical training from vendors

Self-study manuals

Computer-aided instruction

Videotape presentations

Role-playing

Case studies

Experimenting with the AIS under the guidance of experienced users

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

User acceptance forms

Operations documentation

Includes:

Operating schedules

Files and databases accessed

Equipment, security, and file retention requirements

Operations documentation

User documentation

Teaches users how to operate the AIS.

Includes a procedures manual and training materials.

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

Backup and recovery procedures

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

Subsequent walk-throughs are attended by programmers.

Address logical and structural aspects of program code.

Walk-throughs

Processing test transactions

Determines whether the program operates as designed.

Requires both valid and erroneous data.

The correct response for each test should be specified in advance.

Walk-throughs

Acceptance tests

Uses copies of real transactions and files rather than hypothetical ones.

Users develop acceptance criteria.

Then make final decision whether to accept

Walk-throughs

Acceptance tests

Even software purchased from an outside vendor must be tested thoroughly before installation.

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

The process is complete when the new AIS has become a routine, ongoing part of the system.

Conversion Approaches

Four conversion approaches are used to change from an old to a new system:

Direct conversion

Parallel conversion

Phase-in conversion

Pilot conversion

Direct conversion

Parallel conversion

Phase-in conversion

Pilot conversion

Direct conversion

Immediately terminates the old AIS when the new one is introduced.

Appropriate when:

The old AIS has no value; or

The new AIS is so different that comparisons between the two are meaningless.

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 developed and tested.

Direct conversion

Parallel conversion

Phase-in conversion

Pilot 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 differences, and make corrections to the new AIS.

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 gained widespread popularity.

Direct conversion

Parallel conversion

Phase-in conversion

Pilot 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.

Time required to make the complete conversion.

Direct conversion

Parallel conversion

Phase-in conversion

Pilot 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.

Need for interfaces between old and new systems.

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).

A file or database format may be changed.

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.

Document the conversion activities.

Systems Analysis Conceptual Systems Design Physical Design Implementation And Conversion Operation And Maintenance

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 its planned objectives.

Factors and questions include:

Goals and objectives

Does the system help the organization meet its goals, objectives, and overall mission?

Satisfaction

Are users satisfied?

Do they want changes or improvements?

Satisfaction

Benefits

Were the expected benefits achieved?

Satisfaction

Benefits

Costs

Are actual costs in line with expected costs?

Satisfaction

Benefits

Costs

Reliability

Has the system failed, and if so, why?

Satisfaction

Benefits

Costs

Reliability

Accuracy

Does the system produce accurate and complete data?

Satisfaction

Benefits

Costs

Reliability

Accuracy

Timeliness

Does the system produce timely information?

Compatibility

Are hardware, software, data, and procedures compatible with existing systems?

Compatibility

Controls and security

Are there safeguards against unintentional errors, fraud, and intrusion?

Compatibility

Errors

Are there adequate error-handling procedures?

Compatibility

Errors

Training

Are systems personnel and users adequately trained?

Compatibility

Errors

Training

Communications

Is the communications system adequate?

Compatibility

Errors

Training

Communications

Organization changes

Are structural changes that resulted from the system beneficial or harmful?

If harmful, how can they be resolved?

Compatibility

Errors

Training

Communications

Organization changes

Documentation

Is documentation complete and accurate?

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.

User acceptance of that report is the final activity in systems development.

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.

The remaining 70% is spent in maintaining the system—particularly with respect to software modifications and updates.

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 process.

Ais Romney 2006 Slides 20 System Design

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