Analytical Approaches and Diagramming Techniques in Systems Analysis

1. IMS1805Systems Analysis Topic 3: Doing analysis

2. Administration • Class attendance and rolls • First assignment • Sequence of classes from here: • Doing analysis • Diagrammatic modelling techniques

3. 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)

4. 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

5. 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?

6. Sequence Student inserts card Student ID BIS Students Look for student ID In BIS student file Display red light Is student ID valid? No Yes Show green light and unlock door End

7. Hierarchy

8. BIS Students Data movement Read student details Identification details Student ID Valid student IDs Validate Student ID Authorisation

9. Object (and/or person) inter-relationships Student Course Enrols in comprises Unit Unit leader runs

10. Person-process inter-relationships Timetable unit Enrol in unit Lecturer Enrol in tutorials Timetable exam Student Submit results Admin officer Publish results

11. Attitudes ??????????? Blah blah blah …! Lectures Lecturer Students

12. 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

13. 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

14. 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?

15. What do you need to know (and what do you need to tell others)? • Modelling (diagramming), data collection and problem definition as iterative processes Simplistic picture (waterfall) More realistic picture (iteration) Problem definition Data collection Data collection Problem definition System representation (modelling) System representation (modelling)

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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