Transcript Chapter 14 - Accounting and Information Systems Department
Chapter 14
Construct, Deliver, and Maintain Systems Projects
Accounting Information Systems, 5 th edition James A. Hall
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SDLC major phases
1.
2.
3.
4.
5.
Systems strategy Project initiation In-house development Commercial packages Maintenance & support
Chapter 13 Chapter 14
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Systems Development Life Cycle Business Needs and Strategy Legacy Situation Business Requirements System Interfaces, Architecture and User Requirements 1. Systems Strategy - Assessment - Develop Strategic Plan
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Feedback: User requests for New Systems High Priority Proposals undergo Additional Study and Development 2. Project Initiation - Feasibility Study - Analysis - Conceptual Design - Cost/Benefit Analysis
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Selected System Proposals go forward for Detailed Design Feedback: User requests for System Improvements and Support 3. In-house Development - Construct - Deliver
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4. Commercial Packages - Configure - Test - Roll-out New and Revised Systems Enter into Production
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5. Maintenance & Support - User help desk - Configuration Management - Risk Management & Security
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Overview of Phases 3, 4 and 5
Phase 3 - In-House Development appropriate when organizations have unique information needs steps include: analyzing user needs designing processes and databases creating user views programming the applications testing and implementing the completed system
Overview of Phases 3, 4 and 5
Phase 4 - Commercial Packages when acceptable, most organizations will seek commercial software package advantages: lower initial cost shorter implementation time better controls rigorous testing by the vendor risks: must adequately meet end users’ needs must be compatible with existing systems
Overview of Phases 3, 4 and 5
Phase 5 - Maintenance and Support acquiring and implementing the latest software versions of commercial packages making in-house modifications to existing systems to accommodate changing user needs may be relatively trivial, such as modifying an application to produce a new report, or more extensive, such as programming new functionality into a system
Phase 3 In-house Development
3 problems that account for most system failures… 1.
2.
3.
Poorly specified systems requirements
communication problems time pressures
Lack of user involvement
systems developer
in systems development/selection Ineffective development techniques
(for internally developed systems) end user 8
Prototyping
Provides preliminary working version of the system Built quickly and relatively inexpensively with the intention it will be modified End users work with the prototype and make suggestions for changes.
A better understanding of the true requirements of the system is achieved.
Computer-Aided Software Engineering (CASE)
CASE technology uses computer systems to build computer systems.
CASE tools are commercial software products consisting of highly integrated applications that support a wide range of SDLC activities.
PERT charts
Used to show relationship among key activities of a systems project Probably used more for in-house development (than commercial software acquisition) 11
Project Evaluation and Review Technique (PERT)
Deliver Phase Construct Phase
D A A-B 4 Weeks Design Data Model B B-F 5 Weeks Create Data Structures F F-I 3 Weeks Convert Data Files I C E H PERT charts show the relationship among key activities that constitute the construct and delivery process.
Structured Design Approach
A disciplined way of designing systems from the top down Starts with the “big picture” of the proposed system and gradually decomposes it into greater detail so that it may be fully understood Utilizes data flow diagrams (DFDs) and structure diagrams (not necessary to study DFDs)
Systems Design
Follows a logical sequence of events: model the business process and design conceptual views design normalized database tables design physical user views (output and input views) develop process modules specify system controls perform system walkthroughs
Data Modeling
Formalizes data requirements of the business process as conceptual model Entity-relationship diagram (ERD) primary tool for data modeling used to depict the entities or data objects in system Each entity in ER diagram is a candidate for a conceptual user view that must be supported by database.
Normalization
User views in data model must be supported by normalized database tables .
Normalization of database tables: A process of organizing tables so that entities are represented unambiguously Eliminates data redundancies and associated anomalies Depends on the extent that the data requirements of all users have been properly specified in the data model The resulting databases will support multiple user views More detail in chapter 9 about data normalization
Physical User Views: Output Views
Output is the information produced by the system to support user tasks and decisions.
Output attributes: -relevant -summarization -except orientation timely -accurate -complete -concise
Designing Hard Copy Input
Items to Consider: How will the document be handled? How long will the form be stored and in what type of environment?
How many copies are required?
What size form is necessary? Non-standard form can cause printing and storage problems.
Designing System Controls
The last step in the detailed design phase Need to consider: computer processing controls data base controls manual controls over input to and output from the system operational environment controls Allows the design team to review, modify, and evaluate controls with a system-wide perspective that did not exist when each module was being designed independently
Systems Walkthrough
Usually performed by the development team Ensure that design is free from conceptual errors that could become programmed into the final system Some firms use a quality assurance (QA) group to perform this task. An independent group of programmers, analysts, users, and internal auditors
The Delivery
SY S TE M 21
Delivering a system
Appropriate for commercial software or in-house development Test entire system Document the system Designer/Programmer documentation (in-house) Operator documentation (more centralized than distributed) User documentation Accountant/Auditor documentation 22
Conversion of databases
Appropriate for commercial software or in-house development Transfer of data from old system to new system Validate data before conversion Reconcile data after conversion Keep backup copies of old data!
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Converting to New System
Three approaches:
Cold turkey cutover (“Big Bang”)
- firm switches to new system on particular day and simultaneously terminates old system.
Riskiest approach.
Phased cutover
piecemeal fashion. Risk of devastating failure can be reduced.
- modules are implemented in
Parallel cutover
- old system and new system are run simultaneously.
Safest
, yet
costliest
, approach.
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Role of Accountants in Construct & Deliver Phases
Accountant should: Provide technical expertise re: GAAP, GAAS, SEC regulations, SoX, IRS code. Specify documentation standards Verify control adequacy 25
Phase 4 Commercial Packages
4. Commercial Software
Four factors have stimulated
growth of commercial software:
relatively
low cost
prevalence of
industry-specific
growing demand
vendors by small businesses trend of organizational
downsizing distributed data processing
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Types of Commercial Software
Turnkey systems:
tested systems - completely finished and ready for implementation.
Backbone systems: provide basic system structure on which to build.
Vendor-supported systems:
and maintained by vendor custom-developed for customer.
ERP systems are difficult to classify because they have characteristics of all of the above .
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Commercial Software
Advantages Implementation time Cost Reliability Disadvantages Dependence on vendors Need for customized systems Maintenance 29
Steps in Choosing a Commercial Package
1.
2.
3.
4.
Needs analysis Send out
Request for Proposals (RFP)
to prospective vendors to serve as comparative basis for initial screening.
Gather facts
about each vendor’s system using multiple sources and techniques.
Analyze findings and
make final selection.
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Phase 5 Maintenance and Support
Maintenance and Support
Approximately 80% of the life and costs of SDLC Can be outsourced or done in-house End user support is a critical aspect of maintenance that can be facilitated by: knowledge management - method for organizing, refining, and disseminating gathering, user input group memory - method for collecting user input for maintenance and support
The Iceberg Effect
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