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)

Education

data flow

data flow

flow line

feasibility

abdisalam

decision symbol

organisational

differing