Transcript Chapter 3 Study Tool

Systems Analysis & Design
5th Edition
Chapter 3
Requirements Modeling
Phase Description
● Systems analysis is the second of five
phases in the systems development life
cycle (SDLC)
● Uses requirements modeling and
enterprise modeling to represent the
new system
● Before proceeding to the next phase,
systems design, you will consider
system development strategies
2
Introduction
● This chapter describes requirements
modeling techniques and team-based
methods that systems analysts use to
visualize and document new systems
● The chapter then discusses system
requirements and fact-finding
techniques, which include interviewing,
documentation review, observation,
surveys and questionnaires, sampling,
and research
3
Systems Analysis Phase Overview
● Systems Analysis Skills
– Analytical skills
– Interpersonal skills
● Team-Oriented Methods and Techniques
– Joint application development (JAD)
– Rapid application development (RAD)
4
Joint Application Development
● User Involvement
– Users have a vital stake in an
information system and they should
participate fully
– Successful systems must be useroriented and users need to be involved
5
Joint Application Development
● JAD Advantages and Disadvantages
– More expensive and can be cumbersome
– Allows key users to participate effectively
– When properly used, JAD can result in a
more accurate statement of system
requirements, a better understanding of
common goals, and a stronger
commitment to the success of the new
system.
6
Rapid Application Development
● Is a team-based technique that speeds up
information systems development and
produces a functioning information
system
● Relies heavily on prototyping and user
involvement
● Project team uses CASE tools to build the
prototypes and create a continuous
stream of documentation
7
Rapid Application Development
● RAD Objectives
– To cut development time and expense
by involving the users in every phase of
systems development
– Successful RAD team must have IT
resources, skills, and management
support
– Helps a development team design a
system that requires a highly interactive
or complex user interface
8
Rapid Application Development
● RAD Advantages and Disadvantages
– Systems can be developed more quickly
with significant cost savings
– RAD stresses the mechanics of the
system itself and does not emphasize
the company’s strategic business needs
– Might allow less time to develop quality,
consistency, and design standards
9
Modeling Tools and Techniques
● Functional Decomposition Diagrams
– A top-down representation of business
functions and processes
– Also called structure charts
10
Modeling Tools and Techniques
● Functional Decomposition Diagrams
Figure 3-9
11
Modeling Tools and Techniques
● Unified Modeling Language
– A widely used method of visualizing and
documenting software systems design
– provides various graphical tools and
techniques, such as use case diagrams
and sequence diagrams
12
Modeling Tools and Techniques
● Unified Modeling Language
Figure 3-10
13
Modeling Tools and Techniques
● Unified Modeling Language
Figure 3-11
14
Modeling Tools and Techniques
● Unified Modeling Language
Sequence Diagram
Figure 3-13
15
System Requirements Checklist
● System requirement
● Five general categories
– Outputs
– Inputs
– Processes
– Performance
– Controls
16
Future Growth, Costs, and Benefits
● Scalability
– A scalable system offers a better return
on the initial investment
– To evaluate, you need information about
projected future volume for all outputs,
inputs, and processes
17
Future Growth, Costs, and Benefits
● Total Cost of Ownership
– In addition to direct costs, systems
developers must identify and document
indirect expenses that contribute to the
total cost of ownership (TCO)
– Microsoft has developed a method for
measuring total costs and benefits,
called Rapid Economic Justification
(REJ)
18
Fact-Finding
● Overview
– Although software can help you to
gather and analyze facts, no program
actually performs fact-finding for you
– The first step is to identify the
information you need
19
Fact-Finding
● Who, What, Where, When, How, and
Why?
Figure 3-15
20
Fact-Finding
● The Zachman Framework
– A model that asks the traditional factfinding questions in a systems
development context
21
Interviews
● Systems analysts spend a great deal of
time talking with people
● Much of that time is spent conducting
interviews
● Consists of 7 steps
22
Other Fact-Finding Techniques
● Document Review
● Observation
– Seeing the system in action gives you
additional perspective and a better
understanding of the system procedures
– Plan you observations in advance
– Hawthorne Effect
23
Other Fact-Finding Techniques
● Questionnaires and Surveys
– Keep the questionnaire brief and userfriendly
– Provide clear instructions that will
answer all anticipated questions
– Arrange the questions in a logical order,
going from simple to more complex
topics
24
Other Fact-Finding Techniques
● Sampling
– Systematic sample
– Stratified sample
– Random sample
– Main objective of a sample is to ensure
that it represents the overall population
accurately
25
Other Fact-Finding Techniques
● Research
– Newsgroups
– Site visit
Figure 3-23
26
Other Fact-Finding Techniques
● Interviews versus Questionnaires
– When you seek input from a large group
questionnaire is a very useful tool
– If you require detailed information from
only a few people, then you probably
should interview each person
– Interview is more familiar and personal
– Questionnaire gives many people the
opportunity to provide input and
suggestions
27
Documentation
● The Need for Recording the Facts
– Record information as soon as you
obtain it
– Use the simplest recording method
– Record your findings in such a way that
they can be understood by someone
else
– Organize your documentation
28
Preview of Enterprise Modeling
● At the conclusion of requirements
modeling, systems developers should
have clear understanding of business
processes and system requirements
● The next step is to model the logical
design of the system
29
Chapter Summary
● The systems analysis phase includes
three activities
● The main objective is to understand the
proposed project and build a solid
foundation for the systems design phase
● The fact-finding process includes
interviewing, document review,
observation, questionnaires, sampling,
and research.
30
Chapter Summary
● Systems analysts should carefully record
and document factual information as it is
collected, and various software tools can
help an analyst visualize and describe an
information system
● Chapter 3 Complete
31