Acca 12 (systems analysis-user-requirements)

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SYSTEMS ANALYSIS
USER REQUIREMENTS
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Lecture 12
Abdisalam Issa-Salwe
Thames Valley University
Abdisalam Issa-Salwe, Thames Valley University
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Topic list
 Investigating user requirements
 Process models (DFD and
Flowcharts)

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Investigating user requirements
 Fact finding:
 by means of questionnaires, interviews,
observations, reading hand manuals,
organisational charts, etc
 Fact recording:
 using flowcharts, decision tables, narrative
descriptions, organisation and responsibility
 Evaluation:
 assessing strength and weakness of the
existing system
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Systems Investigation
 Techniques used in gathering
information to investigate the
present system include:
 Interviews
 Questionnaires
 Observation and inspection of
records

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Interviews
 Interviews with members of staff
can be the most effective method of
fact-finding.
 Guidelines exists for conducting the
interview.
 Rather than following a standard
routine, the interviewer must be
able to adapt his approach to suit
the individual interviewee and
should be fully prepared for the
interview.
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Interviews (cont…)
 The interviewer should:
 Inform the employee prior to the
interview that a systems investigation is
taking place, explaining its purpose
 Ask questions at a level appropriate to the
employee’s position within the
organisation
 Not be too formal, encouraging the
employee to offer opinions and
suggestions
 Not jump to conclusions or confuse
opinion with fact

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Questionnaires
 Use of questionnaires are useful
when a limited amount of
information is required from a large
number of individuals, or when the
organisation is decentralised with
many separate locations
 Questionnaires may be used in
advance of interviews to save the
analyst’s and employee’s time
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Observation
 Having gained an understanding of the
methods and procedures used in the
organisation
 Observation is a useful way of cross-
checking with the facts obtained by
interview or questionnaire
 Different methods of recording facts
ought to produce the same information,
but it is not inconceivable that staff do
their work one way, while management
believe that they do something different

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User workshops
 A workshop is a meeting with the
emphasis on practical exercise
 User input is obtained by the analyst to
analyse business functions and define the
data associated with the current and
future system
 The workshop may devise to plan for
implementation
 Facilitator to facilitate the workshops.
Facilitator coordinates the workshop
activities
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User workshops (cont…)
 Many user workshop may utilise a
scribe. The scribe is an active
participants who is responsible for
producing the outputs of the
workshops.

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Document review
 The system analyst must
investigate the documents that are
used in the system for input and
output.
 This may be a wide range
investigation, using for example
organisational charts, procedures
manuals and standard operational
forms.
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Existing computerised systems
 Existing computer systems can
provide much information relevant
to the requirements for a new
computerised system.
 It is important to remember
however that a duplicate of the
existing system is not required. The
aim is to produce a better system
which is likely to involve changes to
existing working methods.

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Existing computerised system (cont…)
 Area were an existing system could
provide useful information include:
 File structures
 Transaction volume
 Screen design
 User satisfaction
 User complaints
 Help-desk/information centre records
 Causes of system crashes
 Processor speed
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Systems Analysis
Systems analysis is a detailed look at a
current system and what a new system
will be required to do:
 Leads on directly to systems design, which is
the development of a new system that will
meet these requirements
 Systems analysis is carried out by a systems
analyst, who may either by an employee, or
an external consultant
 The chief analyst, preferably the one who was
also responsible for the feasibility studies, will
work with a team of individuals with differing
backgrounds and experience (technical and
business)

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Systems Analysis (cont…)
 The chief analyst, preferably the
one who was also responsible for
the feasibility studies, will work with
a team of individuals with differing
backgrounds and experience
(technical and business)
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Systems Analysis (cont…)
Systems analysis might be done
in two stages, depending on the
size of the project:
 First stage occurs during the
feasibility study, since this requires
detailing the current system and the
requirements for a new system
 the second stage in the systems
analysis work might be a closer
analysis – leading straight into
design work

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Analysing information flows
 Where does information originate? (Might
come from multiple sources. )
 Which parts should be automated? (Some
things are easier to do without
computers).
 Which automated parts should be
integrated?
 What other systems are involved?
 And what information do they contain?
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Analysis & Design Methods (cont…)
 Data flow diagrams (DFDs), including
context diagrams
 Entity Relationship (ER) Diagram
 Event lists (Entity Life History)
 Pseudocode
Data flow diagrams show how information is passed around
Entity Relationship Models show what information is stored and how it is inter-related
Entity Life Histories show how information is changed during its lifetime

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Data flow diagrams (DFDs)
 DFDs show functional
decomposition, with an emphasis on
the transfer of data in and out of
the system and between program
units.
 DFDs examine how data flows into,
out of, and within the system.
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Data flow diagrams (DFDs) (cont…)
 A Data Flow Diagram is a picture of the
movement of data between external entities and
the processes and data stores within a system.
 Systems analysts use data flow diagrams to help
them model the processes internal to an
information system and how data from the
system’s environment enter the system, are used
by the system, and are returned to the
environment.
 DFDs help analysts understand how the
organization handles information and what its
information needs are or might be.
 Analysts also use DFDs to study alternative
information handling procedures
 During the process of designing new information
services.

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DFD Notation
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A data flow diagram is incomplete unless all its symbols
are labeled as follows:
 Data flow— noun phrase describing the data
 Data store— noun phrase naming the file, database,
or repository where the system keeps data
 Process— verb phrase describing the operation
done on the data. Processes may be labeled with
the name of a system or operation that manipulates
the data

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 Data Flow Diagramming Rules
 Processes cannot have only outputs, cannot have
only inputs, and must have a verb phrase label.
 Data can only move to a data store from a process,
not from another data store or an outside source.
 Similarly, data can only be moved to an outside
sink or to another data store by a process.
 Data to and from external sources and sinks can
only be moved by processes.
 Data flows move in one direction only.
 Both branches of a forked or a joined data flowmust
represent the same type of data.
 A data flow cannot return to the process from which
it originated.
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Flowcharts
 The flowchart is a means of visually
presenting the flow of data through
an information processing systems
 The operations performed within the
system and the sequence in which
they are performed

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Flowcharts (cont…)
 A diagram that uses graphic
 symbols to depict the nature
 and flow of the steps in a
 process.
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Start or end of the program
Computational steps or processing function of a program
Input or output operation
Decision making and branching
Connector or joining of two parts of program
Magnetic Disk
Magnetic Disk
Off-page connector
Flow line
Annotation
Display

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Guidelines in Flowcharting
 The following are some guidelines in
flowcharting:
a. In drawing a proper flowchart, all necessary
requirements should be listed out in logical order.
b. The flowchart should be clear, neat and easy to
follow. There should not be any room for ambiguity
in understanding the flowchart.
c. The usual direction of the flow of a procedure or
system is from left to right or top to bottom.
 Only one flow line should come out from a process
symbol.
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Only one flow line should enter a decision symbol, but two or
three flow lines, one for each possible answer, should
leave the decision symbol.
a.Only one flow line should come out from
a process symbol

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Only one flow line is used in conjunction
with terminal symbol
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 Benefits of Using Flowcharts
 Promote process understanding
 Provide tool for training
 Identify problem areas and
improvement opportunities
 Depict customer-supplier relationships

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 How do we interpret our Flowcharts?
 A Flowchart will help you understand your
process and uncover ways to improve it only if
you use it to analyze what is happening.
Interpreting your Flowchart will help you to:
 Determine who is involved in the process.
 Form theories about root causes.
 Identify ways to streamline the process.
 Determine how to implement changes to the
process.
 Locate cost-added-only steps.
 Provide training on how the process works or
should work.

Acca 12 (systems analysis-user-requirements)

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