Ais Romney 2006 Slides 20 System Design

© 2006 Prentice Hall Business Publishing Accounting Information Systems, 10/e Romney/Steinbart 1 of 171

C 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.


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PrepareConceptual Systems

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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?



• 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 ConsiderationsDesign Considerations


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• 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.




project team develops the conceptual design specifications for the following elements:• Output• Data storage

• How will data be stored to produce the desired outputs?




project team develops the conceptual design specifications for the following elements:• Output• Data storage• Input

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




project team develops the conceptual design specifications for the following elements:• Output• Data storage• Input• Processing procedures and operations

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


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• 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


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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.



• Important design considerations include:– Use of the output

• Who will use it and why?• When is it needed?• What decisions will it facilitate?



• Important design considerations include:– Use of the output– Output medium

• Paper• Screen• Voice response• Diskette• Microfilm• Other



• 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– Graphic



• Important design considerations include:– Use of the output– Output medium– Output format– Pre-printed • Should paper output be on

preprinted form and/or turnaround document?



• Important design considerations include:– Use of the output– Output medium– Output format– Pre-printed– Location • Where is the output to be

sent?



• Important design considerations include:– Use of the output– Output medium– Output format– Pre-printed– Location– Access • Who should be able to

access hard-copy and screen output?



• 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.

• Detailed info goes in an appendix.



• Important design considerations include:– 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



• 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:

– Analysis of impact of a government mandate on profitability



• 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.”• Example:

– Cost overruns



• 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.• 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.


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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 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?


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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



• Considerations in input design include:– Input medium • Keyboard

• OCR• MICR• POS terminal• EDI• Voice input



• Considerations in input design include:– Input medium– Input source

• Where do data originate?– Computer

– Customer

– Remote location



• 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– Source data automation



• Considerations in input design include:– Input medium– Input source– Input format– Input type • What is the nature of the data?



• Considerations in input design include:– Input medium– Input source– Input format– Input type– Volume • How much data are to be entered?



• 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?

• Is additional training necessary?



• Considerations in input design include:– Input medium– Input source– Input format– Input type– Volume– Personnel– Frequency • How often is data to be entered?



• Considerations in input design include:– Input medium– Input source– Input format– Input type– Volume– Personnel– Frequency– Cost

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



• 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?• 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.






• 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

company name and address pre-printed on the form.






• 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.

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






• 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.

• 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.



• 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.




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.





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.


SystemsAnalysis


OutputDesign

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Proce-dures

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• 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.

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• STEP TWO: Develop and document a plan.– Occurs during the conceptual design

phase and the beginning of physical design.

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• 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.

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• 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.

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– 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.

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– 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.

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• 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.

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• STEP SIX: Train program users.– Often uses the program

documentation.

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

together, and the company begins to use the system.

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• 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.

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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



• 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.


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• 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?



• Important control concerns that must be addressed include:– Validity– Authorization

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



• Important control concerns that must be addressed include:– Validity– Authorization– Accuracy • Is input verified to ensure accuracy?

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



• 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?

– Theft of system resources?



• Important control concerns that must be addressed include:– 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?



• Important control concerns that must be addressed include:– 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?



• 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 authorized users?



• Important control concerns that must be addressed include:– Validity– Authorization– Accuracy– Security– Numerical control– Availability– Maintainability– Integrity

• Is processing complete, accurate, timely, and authorized?

• Is it free from unauthorized or inadvertent manipulations?



• Important control concerns that must be addressed include:– 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


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• 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.


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• 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.


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• 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


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• 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



• Three types of documentation must be prepared for new systems:– Development documentation– Operations documentation

• Includes:– Operating schedules– Files and databases accessed– Equipment, security, and file retention requirements



• Three types of documentation must be prepared for new systems:– Development documentation– Operations documentation– User documentation

• Teaches users how to operate the AIS.• Includes a procedures manual and training materials.


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• 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.



• Three common forms of testing include:– 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.



• 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.– Then make final decision whether to accept



• Three common forms of testing include:– Walk-throughs– Processing test transactions– Acceptance tests

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


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• 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– 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.







• 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.







• 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.







• 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.


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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?




– Goals and objectives

– 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

– Controls and security

– 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.

Education

Ais Romney 2006 Slides 20 System Design