chapter 3 requirements modeling. 2 phase description systems analysis is the 2nd of 5 phases in the...
TRANSCRIPT
Chapter 3
Requirements Modeling
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Phase Description
Systems analysis is the 2nd of 5 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, consider some system development strategies
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Chapter Objectives Describe systems analysis phase activities
and the end product, system requirements document
Understand joint application development (JAD) and rapid application development (RAD)
List and describe system requirements, including outputs, inputs, processes, performance, and controls
Explain the importance of scalability in system design
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Chapter Objectives
Define total cost of ownership (TCO) and explain the concept
Conduct a successful interview Develop effective documentation
methods to use during systems development
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Introduction Requirements modeling techniques (fact-
finding) and team-based methods (JAD/RAD) are tools that systems analysts use to visualize and document new systems
System requirements and fact-finding techniques are interviewing, documentation review, observation, surveys and questionnaires, sampling, and research
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Systems Analysis Phase Overview
Uses models and other documentation tools to visualize and describe the proposed system
The deliverable is a system requirements document
Figure 3-2
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Systems Analysis Phase Overview
Systems Analysis Skills Analytical skills Interpersonal skills
Team-Oriented Methods & Techniques Joint application development (JAD) (user involved) Rapid application development (RAD) (mini SDLC)
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Joint Application Development
User Involvement Users have a vital stake in an
information system and they should participate fully
Successful systems must be user-oriented and users need to be involved
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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.
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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
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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
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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
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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
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Modeling Techniques
Functional Decomposition Diagrams A top-down representation of
business functions and processes Also called structure charts
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Modeling Techniques
Functional Decomposition Diagrams
Figure 3-9
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System Requirements Checklist
System requirement Five general categories
Outputs Inputs Processes Performance Controls
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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
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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)
Formula: cost of design, cost of implementation, cost of editing, cost to replace
Plus number of users x days in year used x years before replaced x salary x extra time used per day. Plus lost customer good will, plus lost business.
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Cost and Benefits
Tangible verses Intangible cost Direct verses Indirect Costs Fixed verses Variable Costs Overhead Costs Development verses Operational
Costs Profit verses Cost Center Chargeback methods
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Cost and Benefits ROI – Return on Investment
Benefit – costs = ratio %Total costs
Net Present Value AnalysisNPV = total present value of benefits – total present value of costs
(factored for inflation)
ROI – Return on InvestmentBenefit – costs = ratio %Total costs
Net Present Value AnalysisNPV = total present value of benefits – total present value of costs
(factored for inflation)
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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
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Fact-Finding
Who, What, Where, When, How, and Why?
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Interview
Step 1: Determine the People to Interview Informal structures
Step 2: Establish Objectives Determine the general areas to be
discussed List the facts you want to gather
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Interviews
Step 3: Develop Interview Questions Creating a standard list of interview
questions helps to keep you on track and avoid unnecessary tangents
Avoid leading questions Open-ended questions Closed-ended questions Range-of-response questions
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Interviews
Step 4: Prepare for the Interview Careful preparation is essential
because an important meeting and not just a casual chat
Limit the interview to no more than one hour
Send a list of topics Ask the interviewee to have samples
available
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Interviews
Step 5: Conduct the Interview Develop a specific plan for the meeting Begin with good introduction Use engaged listening Allow the person enough time to think
about the question Summarize main points After interview, summarize the session
and seek a confirmation
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Interviews
Step 6: Document the Interview During the interview, note taking should
be kept to a minimum After the interview, record the information
quickly After the interview, send memo
expressing appreciation, including the main points discussed so the interviewee has a written summary and can offer additions or corrections
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Interviews
Step 7: Evaluate the Interview In addition to recording the facts
obtained in an interview, try to identify any possible biases
Unsuccessful Interviews No matter how well you prepare for
interviews, some are not successful
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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
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Other Fact-Finding Techniques
Questionnaires and Surveys Keep the questionnaire brief and
user-friendly Provide clear instructions that will
answer all anticipated questions Arrange the questions in a logical
order, going from simple to more complex topics
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Other Fact-Finding Techniques
Questionnaires and Surveys Phrase questions to avoid
misunderstandings; use simple terms and wording
Try not to lead the response or use questions that give clues to expected answers
Limit the use of open-ended questions that are difficult to tabulate
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Other Fact-Finding Techniques
Questionnaires and Surveys Limit the use of questions that can raise
concerns about job security or other negative issues
Include a section at the end of the questionnaire for general comments
Test the questionnaire whenever possible on a small test group before finalizing it and distributing to a large group
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Other Fact-Finding Techniques
Sampling Systematic sample (every 10th customer
for review) Stratified sample (% of transactions/shift) Random sample (any 20)
Main objective of a sample is to ensure that it represents the overall population accurately
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Other Fact-Finding Techniques
Research Newsgroups Site visit
Figure 3-23
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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
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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
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Documentation
Software Tools CASE tools Word
processing Spreadsheets Databases
Figure 3-24
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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
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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.
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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