Information Systems in Organisations System Development: The Environment

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

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.

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

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

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

System Characteristics  Components/interrelated components  Boundary  Purpose  Environment  Interfaces  Input  Output  Constraints

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)

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

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

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

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.

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

Categories of ISs  Transaction processing systems  Management information systems  Decision support systems

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

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

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

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

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

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

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

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!

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

References  Essentials of Systems Analysis and Design (Pearson International) 4 th Edition Valacich, George and Hoffer, Chapter 1 Essentials of Systems Analysis and Design