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Transcript of IT1402d
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Requirements
Analysis
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Identifying Requirements
Correct systems can only be built if you know exactly
System Requirements
Defines the services the system is to provide and
prescribe constraints for its operation
Functional
Requirements
Nonfunctional
Requirements
what the
user needswhat the systemmust do
Therefore most important factors in building correctsystems is to first clearly define what the system must do
System Analyst
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Identifying Requirements.System requirements can be developed
by discussing with users their requirements
building systems that satisfy these requirements
Importance of Communication
- Analyst must ensure that no ambiguities arise in discussions
between various people involved in analysis
- Different jargon use by different people may cause problems
Example: Ambiguous Requirement Statement
Identify a transportation to transfer a single
individual from home to place of work
Management
Interpretation IT Interpretation User Interpretation
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Requirements Discovery Methods
Requirements Discovery
Includes techniques to be used by systems analysts to identify
or extract system problems and solution requirements from theuser community.
System Analyst
Requirement discovery for a system
depends on the analysts ability to first
discover and then analyze problems
and opportunities that exist in the
current system
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Requirements Discovery Methods..
It is the formal process of using techniques to collect information about
systems requirements etc. It is also called Information gathering
Fact-Finding
Fact-Finding Methods
Sampling of Existing
documentsResearch
andsite visits
Observations
of the work
environment
Questionnaires
Interviews Prototyping
Joint
requirements
planning
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Requirements Discovery Methods..
First document that analyst should seek
out is the organizational chart
Be sure that they are relevant and
up-to-date
Sampling of existing Documentation
Documentation Forms Files
When you are studying an existing system, you
can get a good idea by studying existing
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Requirements Discovery Methods..Research and Site Visits
Thoroughly research the application and problem.
Good sources ofinformation
Computer trade
Journals
Intranets
Identify the material that are relevant and reliable
Reference books
Internet
World Wide Web
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Requirements Discovery Methods..
Observations of the work environment
Systems Analyst participates in or watches aperson perform activities to learn about the system
often used when validity of data collected through other
methods is in question orwhen the complexity of certain
aspects of the system prevents a clear explanation by theend users.
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Requirements Discovery Methods..
Observations of the work environment
Advantages
Data gathered by observation can be highly reliable
Relatively inexpensive
Allows system analyst to do work measurements
Etc.
Disadvantages
People usually feel uncomfortable when being watched.
Work being observed may not involve the level of difficulty or
volume normally experienced during that time
Etc.
I dont like
being watched
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Requirements Discovery Methods..
Questionnaires
Advantages :
Questionnaires are special purpose documents that allow the
analysts to collect information and opinions from a largeaudience.
Most questionnaires can be answered quickly
Relatively inexpensive way of gathering data.
Allow individuals to maintain anonymity
Responses can be tabulated and analyzed quickly etc.
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Disadvantages:
Requirements Discovery Methods..
Questionnaires
The number of respondents is often low
Mostly suited for close questions
No guarantee that an individual will answer or expand
on all the questions
Good Questionnaires are difficult to prepare
No immediate opportunity to clarify a vague or
incomplete answer to any question.
Etc.
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Types of Questionnaires
Free-format: A question is asked, and the respondent recordsthe answer in the space provided after the question.
Fixed-format: contains questions that require specific responsesfrom individuals
Requirements Discovery Methods..Questionnaires
1. multiple-choice questions
2. rating questions
3. ranking questions
-Given several answers to select one. Eg. Yes, No type
-Given a statement and asked to use supplied responses to
state an opinion.
-Given a several possible answers to be ranked in order of
preference or experience
There are 3 types of fixed-format questions
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Requirements Discovery Methods..
Most commonly used technique
in analysis
Systems analyst collects
information from
individuals face to face.
Systems Analyst must possess
good human relations skills for
dealing effectively with different
type of people
Interviews
Can be used to achieve any of the following goals:find facts, verify facts, clarify facts, generate enthusiasm,
get the end-user involved, identify requirements, and solicit
ideas and opinions.
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Requirements Discovery Methods..
Gives the analyst an opportunity to motivate the
interviewee to respond freely and openly to
questions.
Interviews
Advantages
Allow the analyst to look for morefeedback from the interviewee.
Permit the analyst to ask questions
from each individual etc.
New ideas may arise
Motivation
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Requirements Discovery Methods..
Interviews
Disadvantages
Very time consuming. Therefore costly approach
Success of interviews is highly dependent on thesystems analysts human relations skill.
Interviews may be impractical due to the location of interviewees
etc.
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Requirements Discovery Methods..
Interviews
Types of Interviews
Unstructured interviews..
Types of Interview Questions
Open-ended questions
Closed-ended questions
Structured interviews..
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Requirements Discovery Methods..
Interviews
How to conduct an Interview?
Select Interviewees
Interview the end users of the information system you are studying.
A formal organizational chart will help you identify these
individuals and their responsibilities.
Always make an appointment with the interviewee.
Higher the management level of the interviewees,
less time should be spent.
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Requirements Discovery Methods..
Interviews
How to conduct an Interview?...
Prepare for the Interview
Prepare an interview guide - checklist of specific questions
interviewer will ask the interviewee
Avoid the type of questions such as:
Loadedquestions (Do you need to include both of these columnsfor this report?)
Leadingquestions (You are not going to use this operator code, areyou?)
Biasedquestions (How many codes do we need for foodclassification in the inventory file? I think 20
should cover it ?)
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Requirements Discovery Methods..
Interviews
How to conduct an Interview?...
Prepare for the Interview
Interview question guidelines :
Use clear and concise languageDont include your opinion as part of a
question
Avoid long or complex questions
Avoid threatening questionsverify before you leave
The purpose of the interview is to investigate,
not to evaluate or criticize
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Requirements Discovery Methods..
Interviews
How to conduct an Interview?...
Conduct the Interview
Interview Opening : Intended to influence or motivate theinterviewee to participate
Interview body : Obtain interviewees response to your list ofquestions
Interview conclusion : Express your appreciation. Importantfor maintaining good relationship and trust.
The actual interview
consist of threephases:
Conclusion
Body
Opening
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Requirements Discovery Methods..
Prototyping
A method used to test or illustrate an idea and build a system in an
explorative way. Used to discover user requirements
Allows analyst to quickly create mock forms and tables to simulate
the implemented system.
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Requirements Discovery Methods..Prototyping
Advantages
Allow users and developers to experiment with the software anddevelop with an understanding
Helps to determine feasibility and usefulness of the system
Minimize the time spent for fact-finding and help define morestable requirements. Etc.
DisadvantagesDeveloper may need to be trained in the prototyping
approach
Prototype can only simulate system functionality and are
incomplete in nature. Etc.
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Requirement Discovery Methods
Highly structured group meeting are conducted to analyze problems
and define requirements. JRP is a subset of a more comprehensivejoint application development or JAD technique
JRP Participants
SponsorServe as JRP champion. Single person who is in top management.FacilitatorSingle individual who plays the role of the leader or facilitator.
Joint Requirement Planning (JRP)
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Requirement Discovery Methods
JRP Participants
User and Manger
Number of participants from the user and management.
ScribesThose who are keeping responsible for keeping records pertaining to
everything discussed in the meeting.
IT StaffIT personal who primarily listen and take notes regarding issues and
requirements.
Joint Requirement Planning (JRP)
For more details refer - Ref_1: page 213-239
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Document Analysis
Documents of a SystemDocumentation is both a communication tool and a management
tool.
It is a communication tool : because it contains a repository of all work done to date and
makes it available to all persons working on related parts of alarge project.
Such a repository can prevent unnecessary repetitions whensomeone leaves the project team.
Proper documentation ensures that all the informationdeveloped about the system is always available to new
people joining the project.
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Document Analysis
Documents of a System
Documentation is also a management tool.
It supports management in two ways: gives access to the latest work to all project personnel and
thus reduces the chance of work having to be repeated.
is the only project deliverable, specially in the early project
phases, and thus serves to determine project status and
progress.
Is also a part of the phase output.
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Document Analysis
Document Flow Diagrams
Used to examine the flow of documents within the existing system.
Example: Order
Invoice
Delive
rynotes
Supplier
Purchasing
Dept
Stores
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Document Analysis
Advantages / Usefulness
Used to identify the documentsin the system
Identify the flow of document
To understand the workflow of
the existing system
Used to define the system
boundary
Used to draw Data FlowDiagrams by further analyzing
Etc..
For more details refer - Ref_4: pages 29-34
Document Flow Diagrams