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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