Systems Analysis & Design Sixth Edition Chapter 3 Requirement Modeling

Systems Analysis & Design

Sixth Edition

Chapter 3

Requirement Modeling

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Phase Description

● Systems analysis is the second of five phases in the systems development life cycle (SDLC)

● Uses requirements modeling and data and process modeling to represent the new system

● Before proceeding to the next phase, systems design, you will consider system development strategies

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Systems Analysis Phase Overview

● Systems Analysis Activities– Requirements

modeling– Data and process

modeling– Development

Strategies

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Introduction

● This chapter describes requirements modeling techniques and team-based methods that systems analysts use to visualize and document new systems

● Fact-finding techniques include interviewing, documentation review, observation, surveys and questionnaires, sampling, and research

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● The overall objective is to understand the proposed project, ensure that it will support business requirements, and build a solid foundation for system development

● You use models and other documentation tools to visualize and describe the proposed system

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● Systems Analysis Skills– Analytical skills– Interpersonal skills

● Team-Oriented Methods and Techniques– Joint application development (JAD)– Rapid application development (RAD)

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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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● JAD Participants and Roles– JAD participants should be insulated from

the distraction of day-to-day operations– Objective is to analyze the existing

system, obtain user input and expectations, and document user requirements for the new system

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● JAD Participants and Roles

Figure 3-4

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Figure 3-5

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● JAD Advantages and Disadvantages– Advantages

• Allows key users to participate effectively

– Disadvantages• More expensive and can be cumbersome if

the group is too large relative to the size of the project

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Rapid Application Development

● Rapid application development (RAD) is a team-based technique that speeds up information systems development and produces a functioning information system

● RAD uses a group approach, but goes much further

● The end product of RAD is the new information system

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● RAD Phases and Activities

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● RAD Advantages and Disadvantages– Advantages

• Systems can be developed more quickly with significant cost savings

– Disadvantages• 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

● CASE Tools– Offer powerful modeling features– Systems analysts use modeling and fact-

finding interactively

● Functional Decomposition Diagrams– Functional decomposition diagram (FDD)

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Modeling Tools and Techniques

● Functional Decomposition Diagrams

Figure 3-9

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System Requirements Checklist

● System requirement– After gathering information about new system,

system analyst needs to describe all system requirements.

– A feature that must be included in an IS to satisfy business requirement and be acceptable to users.

● Five general categories– Outputs– Inputs– Processes– Performance– Controls

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● Outputs– The Web site must report online volume

statistics every four hours, and hourly during peak periods

– The inventory system must produce a daily report showing the part number, description, quantity on hand, quantity allocated, quantity available, and unit cost of all parts — sorted by part number

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● Inputs– Manufacturing employees must swipe

their ID cards（刷卡） into online data collection terminals that record labor costs and calculate production efficiency

– The department head must enter overtime hours on a separate screen

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● Processes– The student records system must

calculate the GPA at the end of each semester

– As the final step in year-end processing, the payroll system must update employee salaries, bonuses, and benefits and produce tax data required by the IRS

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● Performance– The system must support 25 users online

simultaneously– Response time must not exceed four

seconds

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● Controls– The system must provide log-on security

at the operating system level and at the application level

– An employee record must be added, changed, or deleted only by a member of the human resources department

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Future Growth, Costs, and Benefits

● Scalability(擴展性）– 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– Total cost of ownership (TCO) is especially

important if the development team is evaluating several alternatives

– One problem is that cost estimates tend to understate indirect costs

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Fact-Finding

● Fact-Finding Overview– The first step is to identify the information

you need

● Who, What, Where, When, How, and Why?– Difference between asking what is being

done (current situation) and what could or should be done (future improvement)

– Know now first, and future comes later

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Fact-Finding

● Who, What, Where, When, How, and Why?

Figure 3-15

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Interviews

● Systems analysts spend a great deal of time talking with people

● Much of that time is spent conducting interviews

● Consists of 7 steps

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Interview

● Step 1: Determine the People to Interview– Informal structures: some people have

more influence or knowledge than appears on an organization chart.

● Step 2: Establish Objectives for the Interview– 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

How is the task performed?– Closed-ended questions

How many pc do you have in this department?– Range-of-response questions

On a scale of 1 to 10, how effective was your training?

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Interviews

● Step 4: Prepare for the Interview– Careful preparation is essential because

an interview is 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

Figure 3-18

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Interviews

Figure 3-19

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Interviews

● Step 5: Conduct the Interview– Develop a specific plan for the meeting– Begin by introducing yourself, describing

the project, and explaining interview objectives

– 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• 50% of a conversation is forgotten within 30

minutes

– 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 your observations in advance

– Hawthorne Effect

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● Questionnaires and Surveys– When designing a questionnaire, the most

important rule of all is to make sure that your questions collect the right data in a form that you can use to further your fact-finding

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● Sampling– Systematic sample– Stratified (分層的） sample– Random sample– Main objective of a sample is to ensure

that it represents the overall population accurately

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● Research– Newsgroups– Site visit

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● Interviews versus Questionnaires– Interview is more familiar and personal– Questionnaire gives many people the

opportunity to provide input and suggestions

● Brainstorming– Structured brainstorming (take turn to

speak)– Unstructured brainstorming (speak when

you have an idea)

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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– Productivity Software

• Word processing, spreadsheets, database management, presentation graphics, histogram

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Documentation

● Software Tools– Graphics modeling software– Personal information managers

• Personal information manager (PIM)• Handheld computers• Personal digital assistants (PDAs)

– Wireless communication devices

Documents

Systems Analysis & Design Sixth Edition Chapter 3 Requirement Modeling