Download - IMS1805 Systems Analysis
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IMS1805Systems Analysis
Topic 3: Doing analysis
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Administration
• Class attendance and rolls • First assignment• Sequence of classes from here:
• Doing analysis• Diagrammatic modelling techniques
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Recap of last lecture
• Some key diagramming techniques used in systems analysis:• Flowcharts (sequence/logic)• Function decomposition diagrams (processes)• Data flow diagrams (processes)• Entity-Relationship diagrams (things and their
relationships)• Object-oriented techniques (objects = process + data)• Soft system techniques (person-system issues)
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Agenda
• Aim: To develop some insights into your own analytical approaches (and diagramming skills
• To note what you need to work on to expand your skills
• To discuss the first assignment and your approach to it
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1. Reviewing your tutorial analytical work
• Look at examples shown in class• Consider them against the sample
analytical/diagramming techniques shown in last lecture (see following slides)
• Which of the analytical approaches/situation aspects did you favour?
• Which of the analytical approaches/situation aspects did you not use?
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Sequence
Student inserts card
Student ID
Look for student IDIn BIS student file
Is student ID valid?
Show green light and unlock door
BIS Students
Yes
Display red light
End
No
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Hierarchy
Calculate overallresult
Calculate exam mark Calculate overallassignment mark
Apply specialconsideration
Calculate firstassignment mark
Calculate secondassignment mark
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Data movement
Read studentdetails
Student
BIS Students
Identification details
Valid student IDs
Authorisation
Validate Student ID
ID
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Object (and/or person) inter-relationships
Student Enrols in
Course
Unit Unit leader
comprises
runs
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Person-process inter-relationships
Enrol in unit
Student
Admin officer
Lecturer Enrol in tutorials
Timetable unit
Timetable exam
Submit results
Publish results
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Attitudes
Blah blah blah …!
???????????
LecturerStudents
Lectures
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Improving your analytical skills
• Dominant focus shown by examples:• Sequence• Actions• Hierarchy (of things)
• Weaker focus shown by examples:• Movement of data/information• Relationships (other than hierarchy)• Attitudes
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Improving your analytical skills
• How appropriate/suitable were the methods you used to the task of describing the situation?
• Selectivity (correctness and suitability of use)?• Could you represent the same situations with a
different technique to highlight a different aspect?
• Need to develop these skills• See examples shown in class
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2. Choosing an analytical/diagrammatic approach
• What are the key aspects of the situation?• What elements/aspects of the situation do
YOU need to understand better?• Who is your audience and what do they need
to know about?• What does the problem demand?
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What do you need to know (and what do you need to tell others)?
• Modelling (diagramming), data collection and problem definition as iterative processes
Problem definition
System representation (modelling)
Data collection Problem definition
Data collection
System representation (modelling)
Simplistic picture(waterfall)
More realistic picture(iteration)
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Being a systems analyst: Living in the middle
• In the middle of the organisation • Going from top-level/management to bottom-level
operations• Analysis at each end and analysis in the middle• The analyst as organisational expert
• In the middle of the development process• Going from user needs to technological capabilities• Analysis at each end and analysis in the middle• The analyst as interpreter
• Choosing the analytical position which suits you and the situation
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3. Some points to consider
• Why use diagrams anyway? (When does text work better/worse?)
• “Logical” vs “physical”• Detail and comprehensibility:
• Partitioning horizontally – how much can you (reasonably) fit on one page?
• Partitioning vertically – how low do you go in terms of detail? (how deep the hierarchy)
• Standards/conventions for symbols and meaning
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Making assumptions
• No data collection about a problem or situation will ever describe all aspects of it fully
• You make assumptions to “fill the gaps” in what you have been told
• This is both necessary and dangerous!• Consider the examples given in the tute – what
did you assume and why?• Always be alert to your assumptions and test
them• Assumptions in your assignment
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Fitting the technique to the task
• Theoretically any technique could be used as part of any type of system development process
• But in practice each technique originated with a particular development approach and tends to be associated with that approach
• Process-oriented – (structured analysis and design, eg waterfall)
• Data-oriented – (information engineering)• Object-oriented – prototyping/RAD environments• Soft systems – socio-technical methods
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4. First assignment
• Assignment requirements• Finding out what you need to know• Developing your explanations of how it works• Testing your assumptions• Selecting diagramming technique(s)• Explaining and justifying your choices
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5. Summary
• You are intuitively familiar with (and therefore biased towards) certain ways of ‘seeing’ and representing situations
• This is both good – you have a starting point to work from; and bad – you will tend to favour these approaches and find it hard to ‘see’ in different ways
• Need to start practising using tute exercises• Develop and demonstrate skills in first
assignment