Transcript Accounting Information Systems 9th Edition

Introduction to Systems
Development Life Cycle
1
The Information Systems
Life Cycle

What are the four steps in the
information systems life cycle
(ISLC)?
1.
2.
3.
4.
System development
System implementation
Syetem operation
System obsolencence
2
3
The Systems Development
Life Cycle

What are the five steps in the
systems development life cycle
(SDLC)?
1.
2.
3.
4.
5.
Systems analysis
Conceptual design
Physical design
Implementation and conversion
Operations and maintenance
4
5
The Systems Development
Life Cycle: Systems Analysis
Systems Analysis
Do initial investigation
Do system survey
Do feasibility study
Determine information needs
and system requirements
Deliver systems requirements
Conceptual
Design
6
The Systems Development
Life Cycle: Conceptual Design
Conceptual Design
Identify and evaluate
design alternatives
Develop design specifications
Deliver conceptual design
requirements
Physical
Design
7
The Systems Development
Life Cycle: Physical Design
Physical Design
Design output
Design database
Design input
Develop programs
Develop procedures
Design controls
Deliver developed system
Implementation
and Conversion
8
The Systems Development
Life Cycle: Implementation and
Conversion
Implementation and Conversion
Develop plan
Install hardware and software
Train personnel, test the system
Complete documentation
Convert from old to new system
Fine-tune and review
Deliver operational system
Operation
and
Maintenance
9
The Systems Development
Life Cycle: Operation and
Maintenance
Operation and Maintenance
Operate system
Modify system
Do ongoing maintenance
Deliver improved system
Systems
Analysis
Feasibility analysis
and decision points:
Economic
Feasibility
Technical Feasibility
Legal Feasibility
Scheduling
Feasibility
Operational
Feasibility
10
Planning Systems
Development

Why is planning an important step in
systems development?
–
–
–
–
–
consistency
efficiency
cutting edge
lower costs
adaptability
11
Planning Systems
Development

What types of systems development
plans are needed?
–
–
project development plan
master plan
12
Planning Techniques

Two techniques for scheduling and
monitoring systems development activities
are:
1
PERT (program evaluation and review
technique)
• PERT requires that all activities and the precedent
and subsequent relationships among them be
identified.
2
Gantt chart
• A bar chart with project activities listed on the lefthand side and units of time across the top
13
Planning Techniques:
Gantt Chart
Project Planning Chart
(Sample
Gantt
Chart)
______________________________________________
Activity
Week Starting
______________________________________________
1
______________________________________________
2
______________________________________________
3
______________________________________________
4
______________________________________________
5
______________________________________________
6
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7
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8
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14
Gantt Chart
4-15
PERT Chart
4-16
Microsoft Project Gantt Chart
4-17
Microsoft Project PERT Chart
4-18
Systems Analysis

There are five steps in the analysis
phase:
1.
2.
3.
4.
5.
Initial investigation
Systems survey
Feasibility study
Information needs and systems
requirements
Systems analysis report
19
Systems Analysis
When a new or improved system is
needed, a written request for systems
development is prepared.
 The request describes the current
system’s problems, why the change is
needed, and the proposed system’s
goals and objectives.
 It also describes the anticipated
benefits and costs.

20
Sample Request for System Services
5-21
Sample Problem Statements
5-22
Feasibility Analysis



Systems analysis is the first step in the
systems development life cycle (SDLC).
A feasibility study (also called a business
case) is prepared during systems analysis
and updated as necessary during the
remaining steps in the SDLC.
The steering committee uses the study to
decide whether to terminate a project,
proceed unconditionally, or proceed
conditionally.
23
Feasibility Analysis

What five important aspects need to
be considered during a feasibility
study?
1.
2.
3.
4.
5.
Technical feasibility
Operational feasibility
Legal feasibility
Scheduling feasibility
Economic feasibility
24
Feasibility Analysis
Economic feasibility is the most
frequently analyzed of the five
aspects.
 What is the basic framework for
feasibility analysis?

–
capital budgeting model
25
Feasibility Analysis

What are some capital budgeting
techniques?
–
–
–
payback period
net present value (NPV)
internal rate of return (IRR)
26
Candidate Systems Matrix
5-27
Candidate Systems Matrix (cont.)
5-28
Feasibility Matrix
5-29
Typical System Proposal Outline
I.
II.
III.
IV.
V.
VI.
Introduction
A. Purpose of the report
B. Background of the project leading to this report
C. Scope of the report
D. Structure of the report
Tools and techniques used
A. Solution generated
B. Feasibility analysis (cost-benefit)
Information systems requirements
Alternative solutions and feasibility analysis
Recommendations
Appendices
5-30
Computer-Aided Software
Engineering (CASE)



CASE is an integrated package of
computer-based tools that automate
important aspects of the software
development process.
CASE tools are used to plan, analyze,
design, program, and maintain an
information system.
They are also used to enhance the efforts
of managers, users, and programmers in
understanding information needs.
31
Computer-Aided Software
Engineering (CASE)


CASE tools do not replace skilled
designers; instead they provide a host of
self-integrated tools that give developers
effective support for all SDLC phases.
CASE software typically has tools for
strategic planning, project and system
management, database design, screen and
report layout, and automatic code
generation.
32
CASE Tool Architecture
3-33
Computer-Aided Software
Engineering (CASE)
Advantages of CASE Technology
Improved productivity
Improved program quality
Cost savings
Improved control procedures
Simplified documentation
34
Computer-Aided Software
Engineering (CASE)
Disadvantages of CASE Technology
Incompatibility
Cost
Unmet expectations
35
Systems Design,
Implementation, and
Operation
36
Conceptual Systems Design


In the conceptual systems design phase,
a general framework is developed for
implementing user requirements and
solving problems identified in the analysis
phase.
What are the three steps in conceptual
design?
1.
2.
3.
Evaluate design alternatives.
Prepare design specifications.
Prepare conceptual systems design report.
37
Conceptual Systems Design
Systems
analysis
Evaluate
design
alternatives
Prepare
design
specifications
Prepare
conceptual
systems
design report
38
Conceptual Systems Design


Evaluate design alternatives:
The design team should identify and
evaluate design alternatives using the
following criteria:
How well it meets organizational and
system objectives
2. How well it meets users’ needs
3. Whether it is economically feasible
4. Its advantages and disadvantages
1.
39
Conceptual Systems Design


Prepare design specifications:
Once a design alternative has been
selected, the team develops the
conceptual design specifications for the
following elements:
Output
2. Data storage
3. Input
4. Processing procedures and operations
1.
40
Conceptual Systems Design


Prepare conceptual systems design
report:
At the end of the conceptual design a
conceptual systems design report is
developed and submitted.
To guide physical systems design activities
2. To communicate how management and
user information needs will be met
3. To help assess systems’ feasibility
1.
41
Physical Systems Design

Physical design translates the broad,
user-oriented AIS requirements of
conceptual design into detailed
specifications that are used to code
and test the computer program.
Conceptual
systems design
Physical
systems design
42
Physical Systems Design:
Output Design


The objective of output design is to
determine the characteristics of
reports, documents, and screen
displays.
Output fits into one of four
categories:
Scheduled reports
2. Special-purpose analysis
3. Triggered exception reports
4. Demand reports
1.
43
Physical Systems Design:
File and Database Design

What are some file and database
design considerations?
–
–
–
–
–
medium of storage
organization and access
processing mode
maintenance
size and activity level
44
Physical Systems Design:
Input Design


When evaluating input design, the
design team must identify the
different types of data input and
optimal input method.
What are the two principal types of
data input?
1. Forms
2. Computer screens
45
Physical Systems Design:
Program Design



Program design is one of the most timeconsuming activities in the entire SDLC.
Programs should be subdivided into small,
well-defined modules to reduce complexity.
What is this referred to as?
–

structured programming
Modules should interact with a control
module rather than with each other.
46
Physical Systems Design:
Procedures Design
Procedures design should answer the
who, what, where, and how questions
related to all AIS activities.
 What should procedures cover?





input preparation
transaction processing
error detection and corrections
controls
47
Physical Systems Design:
Procedures Design
What should procedures cover?
(continued)
 reconciliation of balances
 database access
 output preparation and distribution
 computer operator instructions
48
Physical Systems Design:
Control Design
What are some control design considerations?
Validity
Authorization
Accuracy
Security
Numerical Control
Availability
Maintainability
Integrity
Audit Control
49
Physical Systems
Design Report
At the end of the physical design
phase the team prepares a physical
systems design report.
 This report becomes the basis for
management’s decision whether to
proceed to the implementation phase.

50
Systems Implementation

Systems implementation is the
process of installing hardware and
software and getting the IS up and
running.
51
Systems Implementation
Implementation planning
Develop and
test software
programs
Prepare site;
install and
test hardware
Complete
documentation
Select
and train
personnel
Test system
Conversion
52
Systems Implementation:
Implementation Planning
An implementation plan consists of
implementation tasks, expected
completion dates, cost estimates,
and the person or persons
responsible for each task.
 Planning should include
adjustments to the company’s
organizational structure.

53
Systems Implementation:
Develop and test software
programs
Seven steps are followed when developing
and testing software programs.
1.
2.
3.
4.
5.
6.
7.
Determine user needs.
Develop a plan.
Write program instructions (code).
Test the program.
Document the program.
Train program users.
Install and use the system.
54
Systems Implementation:
Site Preparation



A PC requires little site preparation.
A large system may require
extensive changes, such as
additional electrical outlets.
Site preparation should begin well in
advance of the installation date.
55
Systems Implementation:
Select and train personnel
Employees can be hired from outside
the company or transferred internally.
 Effective IS training should include
employees’ orientation to new policies
and operations.
 Training should occur before systems
testing and conversion.

56
Systems Implementation:
Complete Documentation

Three types of documentation must
be prepared for new systems.
1.
2.
3.
Development documentation
Operations documentation
User documentation
57
Systems Implementation:
Test the System

There are three common forms of
testing.
1.
2.
3.
Walk-through
Processing of test transactions
Acceptance tests
58
Systems Implementation:
Conversion

There are four conversion
approaches.
1.
2.
3.
4.
Direct conversion
Parallel conversion
Phase-in conversion
Pilot conversion
59
Systems Implementation
Direct Conversion Method
Old system
New system
60
Systems Implementation
Parallel Conversion Method
Old system
New system
61
Systems Implementation
Phase-in Conversion Method
Old system
New system
62
Systems Implementation
1
Pilot Conversion Method
3
2
1
2
3
Old Old Old
1
Old Old New
2
3
Old New New
1
2
3
New New New
63
Systems Implementation:
Data Conversion

Data files may need to be modified
in three ways:
1.
2.
3.
Files may be moved to a different
storage
Data content may be changed
File format may be changed
64
Operation and Maintenance
The final step in the SDLC is to
operate and maintain the new system.
 A postimplementation review should
be conducted on a newly installed
system.

Implementation
and conversion
Operation and
maintenance
65
Operation and Maintenance
What are some factors to consider during the
postimplementation review?
Goals and objectives
Controls and security
Satisfaction
Errors
Benefits
Training
Costs
Communications
Reliability
Organizational changes
Documentation
Accuracy
Timeliness
Compatibility
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