IT Systems Analysis and Design

1. IT Systems Analysis and Design • a method used by companies to create and maintain information systems that perform basic business functions • main goal is to improve organisational systems

2. SAD (Core Concepts) • analysis and design process usually involves developing or acquiring application software, which is designed to support a specific organizational function or process.

3. Methodologies & Techniques • methodology is a sequence of step-by-step approaches that help develop the information system • techniques are processes that need to be followed to help ensure that the work is complete and comprehensible

4. Tools • computer programs such as computer-aided software engineering (CASE) tools, that make it easy to use specific techniques

5. What is a system? • A group of interrelated procedures used for a business function, with an identifiable boundary, working together for same purpose. • examples – payroll system, inventory system, student registration system

6. System Characteristics • Components/interrelated components • Boundary • Purpose • Environment • Interfaces • Input • Output • Constraints

7. System Characteristics • An irreducible part or aggregation of parts that makes up a system (also called a subsystem) • Interrelated component – the function of one component is somehow tied to the function of others (e.g. customer records need to be sorted before a report is produced)

8. System Characteristics Boundary • The line that marks the inside and outside of a system and that sets off one system from another system • Systems outside the boundary cannot be changed – e.g. a customer system will be for customers only and not include the public

9. Purpose & Environment • The overall goal or function of a system • Environment – everything external to the system that interacts with the system

10. Interface and Constraint • Interface – point of contact where a system meets its environment or where subsystems meet each other. • Constraint – a limit to what a system can accomplish

11. System Concepts • Decomposition – the process of breaking the system into smaller components (which in turn can be broken down as well) • Modularity – dividing a system into modules of equal size • Coupling – the extent to which the systems depend on each other • Cohesion – the extent to which a subsystem performs a single function.

12. System Analyst • Person most responsible for the analysis and design of information systems • Primary role is to study the problems and needs of the organization in order to bring about improvements • Person needs to possess analytical, technical, managerial and interpersonal skills

13. Categories of ISs • Transaction processing systems • Management information systems • Decision support systems

14. Transaction Processing System • TPS automates the handling of data about business activities and transactions(high volume/data capture focus) • Examples – supermarket cash register, bank machines, retailer POS • Goal is to processing up and improve efficiency and accuracy • Process orientation

15. Management Information System • MIS is a computer based system that takes the raw data available through a TPS and converts it into a meaningful aggregated form. • Examples sales reports – which items sell well and which are slow selling items. • Data orientation – understand relationships between data

16. Decision Support System • DSS is designed to help decision makers with decisions. • It allows people making the decisions to quickly manipulate data • What if analysis • Usually DSSs are used by higher management • Data and decision logic orientation

17. System Development Methodology • A standard process followed by organization to conduct all the steps necessary to analyze, design, implement and maintain information systems • Systems Development Life Cycle (SDLC) is a commonly used methodology • Planning and selection • Analysis • Design • Implementation and Operation

18. SDLC (Planning & Selection) • An organization’s total IS needs are analyzed and • A potential IS project is identified and decision is made whether the project will continue or not • A feasibility study is conducted • Investigation of the system’s scope is also determined

19. SDLC (System Analysis) • The current system is studied and alternative replacement systems are proposed • System requirements are determined (e.g. user needs!) • Alternative solutions are recommended

20. SDLC (System Design) • The chosen system (to be developed) is described independently of any computer platform (logical design) • Then transformed into technology-specific details (physical design) from which all programming and system construction can be accomplished

21. SDLC (Implementation & Operation) • Information system is coded, tested and installed in the organization • Information system is systematically repaired and improved • System specifications are turned into a working system that is tested and then put into use! • Even a well designed system can fail if implementation is not managed well!

22. Approaches to Development • Prototyping • Computer-aided software engineering (CASE) • Joint application design (JAD) • Rapid Application Development (RAD) • Participatory design • Agile Methodologies

23. References • Essentials of Systems Analysis and Design(Pearson International) 4th EditionValacich, George and Hoffer, Chapter 1