Unit 3 : Information Systems

Conducted by: Computer Science Society Of University Of Colombo

Parakrama Ratnayake

What is a System ?What is a System ?

It is a collection of It is a collection of interrelatedinterrelated componentscomponents that work together to that work together to perform a specific task.perform a specific task.

e.g. : e.g. :

Human BodyHuman Body

Business OrganizationBusiness Organization

A ComputerA Computer

Sub Systems ?Sub Systems ?

In a System the different components are connected with In a System the different components are connected with each other and they are each other and they are interdependentinterdependent. . Each Each component is a component is a Sub SystemSub System of the original system of the original system and carries out part of the systems tasks.and carries out part of the systems tasks.

e.g. :e.g. :Parts like digestive system in the Parts like digestive system in the

human bodyhuman body

The marketing branch of a business The marketing branch of a business organization organization

Elements of a SystemElements of a System

Input OutputProcessing

Basically there are three major components in every system, namely input, processing and output.

The System is separated from the external environment from the system boundary.

The system receives inputs from a its environment and returns outputs to the environment by processing the inputs.

Input Output

•Sub systems should communicate with each other in order to process an output to a particular input.

•One subsystems output will be an input to another.

•A good system will be made up of highly independent subsystems with minimal flows between them.

DATA vs. DATA vs. INFORMATIONINFORMATIONDataData Raw facts in isolation. Data describe the business. These are isolated facts convey meaning but generally are not useful by themselves.

InformationInformation is data that has been manipulated to be useful to someone. In other words, information must have value, or it is still data. Information tells people something they don’t already know or confirms something that is suspect.

Important factsImportant facts

• Most people use the terms data and information interchangeably. But data and information are not the same thing.

• One person’s information may be another person’s data.

Information SystemInformation System

An arrangement of people, data, processes, An arrangement of people, data, processes, interfaces, networks and technology that are interfaces, networks and technology that are integrated for the purpose of supporting and integrated for the purpose of supporting and improving the day to day operations in a improving the day to day operations in a business, as well as fulfilling the problem solving business, as well as fulfilling the problem solving and decision making information needs of and decision making information needs of business managers. business managers.

Two Main Types of Information SystemsTwo Main Types of Information SystemsManual Information SystemsManual Information SystemsComputer Based Information SystemsComputer Based Information Systems

Manual Information Systems

File storage devices, manual procedures and papers are examples of components of a manual information system.

Computer bases Information System

Involves six interdependent components:

Hardware (machines)

Software (instructions & programs)

People (programmers, managers and users)

Procedures (rules)

Data & Information

Pros & Cons of a Manual Pros & Cons of a Manual Information SystemInformation System

ProsPros FlexibleFlexible Judgments & Decisions can be taken easily by Judgments & Decisions can be taken easily by

humanshumans

ConsCons Humans are unreliableHumans are unreliable Slow in performing arithmetical operationsSlow in performing arithmetical operations Subjected to fatigue and boredomSubjected to fatigue and boredom

Levels of ManagementLevels of Management

Upper or Top or Strategic Management

Middle or Tactical Management

Lower or Operational level Management

Three levels of management

Strategic

Tactical

Operational

Levels of Management cont..Levels of Management cont..

Each level of management can be Each level of management can be distinguished by the types of distinguished by the types of

Decisions made Time frame considered in the decisions Types of report information needed to make

decisions

Lower or Operational level Management

They make structured decisions (Operational decisions).They make structured decisions (Operational decisions). Structured decision It’s a predictable decision that can Structured decision It’s a predictable decision that can

be made following a well defined set of routine be made following a well defined set of routine procedures. procedures.

Most decisions at this level require easily defined Most decisions at this level require easily defined information that relates to the current status and information that relates to the current status and activities within the basic business functions.activities within the basic business functions.

Information is gained from detailed reports which contain Information is gained from detailed reports which contain information about routine activities.information about routine activities.

Detailed tasks defined by middle management are Detailed tasks defined by middle management are carried out by people at operational level.carried out by people at operational level.

Middle or Tactical Management

Acquire and arrange the resources (Computers, people etc) to meet Acquire and arrange the resources (Computers, people etc) to meet the goals of an organization.the goals of an organization.

Define the detailed tasks to be carried out at the operational level.Define the detailed tasks to be carried out at the operational level. Information needed involves review, summarization and analysis of Information needed involves review, summarization and analysis of

data to help plan and control operations and implement policy that data to help plan and control operations and implement policy that has been formulated by upper management.has been formulated by upper management.

Information is usually given to middle managers as summarized Information is usually given to middle managers as summarized reports.reports.

Deals with semi structured decisions. (Tactical decisions)Deals with semi structured decisions. (Tactical decisions) Semi structured decisions that must be made without a base of clearly Semi structured decisions that must be made without a base of clearly

defined informational procedures. In most cases a semi structured defined informational procedures. In most cases a semi structured decision is complex, requiring detailed analysis and extensive decision is complex, requiring detailed analysis and extensive computations. computations.

Upper or Top or Strategic Management

Decides on the broad objectives of an Decides on the broad objectives of an organization.organization.

Make unstructured decisions. (Strategic Make unstructured decisions. (Strategic decision).decision). Unstructured decisions are the most complex Unstructured decisions are the most complex

type of decisions and are rarely based on type of decisions and are rarely based on predetermined routine procedures. They predetermined routine procedures. They involve subjective judgments of the decision involve subjective judgments of the decision maker.maker.

Types of Information SystemsTypes of Information Systems

•Transaction processing systems (TPS)

•Management Information Systems (MIS)

•Decision support Systems (DSS)

•Executive Information Systems (EIS)

•Expert Systems (ES)

Transaction Processing Systems (TPS)

•These systems capture and process data about business transactions.

•Some times called as data processing systems

•Mostly used at operational level

•Usually creates detailed reports of daily transactions or future transactions

•Reports generated are useful only to lower level managers

•One functional area of a business consists of an TPS

Management Information Systems (MIS)

•Provides middle level management with reports that summarize and categorize information derived from company databases. (In pre determined format)

•Supplements Transaction processing Systems

•Able to produce detailed information, summary information, exception information

•Information produced is based on accepted management or mathematical/statistical models

Decision Support Systems (DSS)Decision Support Systems (DSS)

•Provides its users with decision oriented information whenever a decision-making situation arises

•Analyses information already captured by TPS and MIS in order to support unstructured decision making at top management level

•Facts

•DSS does not make decisions, it helps some one to make a decision by providing information

•TPS or MIS does not analyze information they produce

Executive Information System (EIS)Executive Information System (EIS)

•Is a DSS which is especially meant for top level management and specifically support unstructured decision making

•Also called Executive Support Systems (ESS)

•Draws data not only from the organization, able to draw information from outside sources such as news services and marketing –research databases.

Expert Systems (ES)Expert Systems (ES)•Captures knowledge expertise of a problem solver or decision maker and then simulates thinking of that expertise for those who have less expertise.

•Includes logic and reasoning within there respective fields

•Facts

•Emerged from the filed of artificial intelligence (Creating computer systems that simulate human reasoning and sensation)

System Development Life Cycle (SDLC)System Development Life Cycle (SDLC)

Problem Definition

Testing

Implementation

Software DevelopmentSoftware Development

Maintenance

System AnalysisSystem Analysis

Feasibility StudyFeasibility Study

System DesignSystem Design

SDLC cont..SDLC cont..

Every system has a life cycle. Be it a computer Every system has a life cycle. Be it a computer or humanor human

SDLC is an organizational process of developing SDLC is an organizational process of developing an information system to solve business an information system to solve business problems and needsproblems and needs

SDLC means combinations of various activities. SDLC means combinations of various activities. These activities are called phases and the SDLC These activities are called phases and the SDLC consists of many phases consists of many phases

Also called Classical Life Cycle Model, Linear Also called Classical Life Cycle Model, Linear Sequential Model or Water Fall ModelSequential Model or Water Fall Model

Phase 1: Problem DefinitionPhase 1: Problem Definition

•Provides a broad statement of user requirements, which in other words is what the user expects the systems to do

•Sets the direction for the whole project

•Also sets the project bounds, which define what part of the system can be changed by the project and what parts remain the same

•The resources to be made available to the system are also specified in this phase

Phase 2 : Feasibility StudyPhase 2 : Feasibility Study

•Determines whether a particular project is technically and economically feasible

•Determines the best method to achieve the objectives of the new information system

•Outcome of this phase is a recommendation of a new system proposal

•This proposal is to agreed by the higher management in consultation with department managers.

Phase 3 : System AnalysisPhase 3 : System Analysis•System analysts studies the existing system in detail, leading to specifications of a new system. This is carried out by gathering facts.

Facts gathering techniques

• Inspection of written documents

• Interviews

• Questionnaires

• Site Observations

•Gathered data must be analyzed and documented in data flow diagrams, data dictionary, logical data structures and miniature specifications.

•The system is broken down into smaller sub processors during this phase.

•At the end of the phase the System analyst has to produce a detailed report on the specifications of the new system.

System AnalystSystem Analyst

Person who facilitates the development of information systems and computer applications

He/ She should be able to

Asses situations and draw conclusions

Possess a strong general business orientaion

Speak and write effectively

Prepare clear concise reports

Work well with others to gain confidence and respect from them

Phase 4 : System DesignPhase 4 : System DesignProduces a logical design specification for the new system.

The analyst

schedules design activities

works with user to determine the various data inputs to the system

plan how data will flow through the system

designs required outputs

writes program schedules

During design, the analyst

Draws a model of the new system, using dataflow diagrams and entity relationship diagrams

Devises formats for all the reports that the system will generate

Develops a method for collecting and inputting data

By the end of this phase the analyst has to contd..

Defines detailed data requirements with a data dictionaryWrites program specificationsSpecifies control techniques for the system’s outputs, database and inputsIdentifies and orders any hardware or software that the system will need

By the end of this phase the analyst has to

prepare complete systems specifications in form of a detailed report

(this report contains step by step instructions that describes the proposed system)

Phase 4 : System Design contd..Phase 4 : System Design contd..

Phase 5 : Software DevelopmentPhase 5 : Software Development

•Design specifications are converted into source code of a programming language.

•Programmers carry out these tasks.

•Software that is to be developed, is divided into many modules according to the subdivisions in phase 3. These modules are created independently and then tested individually. This type of testing is called unit testing)

Phase 6 : TestingPhase 6 : TestingThe system should be fully tested for errors (bugs) before implementation.

Two types of tests are conducted

1. Integration testing

After completion of unit tests of all modules, the modules are to be combined and be tested. At this stage the test is done on actual data

2. Acceptance testing

Acceptance criteria is the agreement made between the user and the system developer. The acceptance criteria contains a

list of important requirements that the system has to satisfy. The tests conducted to check the acceptance criteria are called acceptance testing.

Phase 7 : ImplementationPhase 7 : ImplementationThe phase contains two activities

1. The user training

The users are to be given training for operating a new information system. Main topics of such type of training are

How to execute the package

How to enter data

How to process data

How to take reports

2. The conversion

The process of replacing an existing system with a new system is called conversion. Conversion of the system may proceeds in four ways.

Direct Implementation The entire system is replaced with the new system in

one go. Parallel Implementation

Both systems i.e. the new and the old systems are executed in parallel for a certain defined period of time. This strategy is helpful because of the following

Results of the old system can be compared with the results of the new system

Failure of the new system at the early stage, does not affect working of the organization

Phased implementation The new system is introduced in a phased manner

Pilot implementation New system installed in parts and executed

successfully for a considerable time period. When the results are found satisfactory then only the other parts are implemented

Phase 8 : MaintenancePhase 8 : Maintenance

Eliminates errors in a system during it’s life time Eliminates errors in a system during it’s life time and to tune the system to any variations.and to tune the system to any variations.

It also means the review of the system from time It also means the review of the system from time to time.to time. The review is done for The review is done for

Knowing the full capabilities of the systemKnowing the full capabilities of the system Knowing the required changes or the additional requirementsKnowing the required changes or the additional requirements Studying performanceStudying performance

If a major change to a system is needed a new If a major change to a system is needed a new project may have to be setup.project may have to be setup.

Problems in system developmentProblems in system development

Estimating cost and timeEstimating cost and time Selecting a project teamSelecting a project team Capturing user requirementsCapturing user requirements Using standardsUsing standards Choosing design approachesChoosing design approaches Coding programCoding program Testing programsTesting programs Maintaining systemsMaintaining systems