Chapter 9. System Analysis & Design

Chapter 9. System Analysis & Design

An orderly grouping of independent components linked together to achieve a specified goal/objective.

Eg:-

ü  Human Body

ü  School

ü  Hospital

ü  Supermarket

ü  Bank

ü  Factory….

Characteristics of System

•         Organisation               àArrangements of components.

•         Interaction                            à Communication of each component.

•         Interdependence               à Depending of one component to another

•         Integration                           àMore than one components working together.

•         Central objective                àMain/Common goal (Highest priority.)

System Analysis & Design (SAD)

It is the process of examining the situations of existing or new system to increase its productivity and efficiency by adding better procedures and methods. For this system development lifecycle (SDLC) is used.

System Development Life Cycle (SDLC)

A set of activities used for developing a new system or changing an existing system. A structured sequence of phases for implementing a business/other information system

Phases of SDLC

•         Preliminary study or survey

•         Feasibility study

•         Analysis

•         Design

•         Development and testing

•         Implementation

•         Maintenance and review

SDLC

Preliminary study or Survey

Feasibility Study

Analysis

Design

Development & Testing

Implementation

Maintenance & Review

1. Preliminary Study/Survey

In this step we recognise or determining system needs.

Objectives:

•         Set the scope, limitations and objectives of the system.

•         Make good relationship with the users.

•         Estimate the resource and maintenance cost.

•         Identify the new system benefits.

2. Feasibility Study

          Checking the requested system is affordable or not. Here test the proposed system by its workability, impact on org., solving the user’s need, usage of resources etc.

Objectives:

•         Existing system evaluation.

•         Analyse the new system procedures.

•         Cost estimation.

•         Make feasibility study report for the organisation

(Feasibility report includes, Statement of the problem, Summary of findings, Details of findings, Recommendations and conclusion)

Types of feasibilities

·        Technical: It deals with the hardware & software requirements for the system.

·        Economical: It includes the cost benefit checking for the new system.

·        Operational: It deals with the behavioural or it depends the operators or users in the system.

3. Analysis

It is an activity that takes place when new information system is being developed or existing systems are changed. It includes detailed evaluation of the system and data collection

System Analyst

A person who is responsible for the Analysis, Design and Implementation of a business system on the computer is called System Analyst.

Qualities of a System Analyst

·        Communication Skill

·        Understanding Skill

·        Problem Solving Skill

·        Varied Skill

·        Business Knowledge

·        Technical Knowledge

Analysis Tools          The tools for detailed evaluation are data flow diagram, Data dictionary, structured English, decision tree, decision table.

•         Data Flow Diagram (DFD)
(Graphical Representation of Data Movement)

Data Flow, Process, Data storage, System Data

•         Data Dictionary
(Names of all Data Items Used in the System)

•         Structured English
(Pseudo Codes. Communicating. Processing Rules/Structure)

•         Decision Tree
(Graphical Representation of Logical Conditions /Actions)

•         Decision table /
(Chart of Logical Conditions /Actions)

Fact Finding Techniques
          The data Collection tools are as follows,

·        Interview

·        Questionnaire

·        Onsite Observation

·        Sampling

Interview

It is a data collection method from a business firm in which the responsible persons have no time to write answers in a questionnaire.

Guidelines to a Successful Interview

•         Set the time, date and place for the interview.

•          Prepare questions to solve the objectives and record the answers

•          Choose the right person for interview.

•          Get authorization from the company head.

•          Be a good listener, avoid arguments.

•          Prepare report after the interview.

Questionnaire

It is a data collection method in which we can collect the data from a large number of persons. Here we can’t view the expressions of the respondent (Limitation).

Guidelines for a good questionnaire

•         Questions should be clear, unambiguous and avoid negative questions.

•         Relevant questions should be included.

•         It should be brief and self explanatory.

•         Question should be to get the expected answers.

Adv: - Economical, it need less skill, respondent have great confidence

Onsite Observation

It is useful when we can’t get the data from other methods. By using this analyst get first hand information by observing the activities in the system. 

Sampling

It is applicable when the transactions are large. Here a random sample is selected for the whole.

4. Design

It is the process of applying various techniques and principles for the purpose of defining a system with sufficient details to its physical realization.  For this review the present system through the analysis process.

Steps involved in Design

•         Input design: To convert user generated inputs to computer format. Identify the source (Data capture), Conversion (Data entry), Send to memory for processing by the program (Data input).

•         Output Design: Define the nature of the report that correct to the inputs. It may be documents, lengthy reports, graphs etc.

•         File design:  Collection of records with fields. They are logical records.(Master files, Transaction files, Work files, Backup files, Audit files).

•         System processing and general program design: Design Program for each section with I/O and process. A system flowchart is used here.

5. Development and testing

•         Develop detailed programming specifications.

•         Develop test specification and test data.

•         Write computer programs.

•         Test computer programs.

•         User training.

•         System testing.

•         File conversion.

•         Change over to the new system.

6. Implementation (Change over)

•         Parallel-New system operated with old system.

•         Direct-Old system replaced by new system.

•         Pilot- A part of new system implemented.

•         Phase in- Gradual implementation.

7. Maintenance & Review

          Maintenance is the process of changing a system after it has been delivered and in use is called maintenance. Review means checking the whole system whether it achieve the objectives or goal. Maintenance are 3 types, they are

•         Corrective- Repairing failures due to previously ill defined problems

•         Adaptive- Correcting a problem or upgrading the performance when a need arise

•         Perfective- Enhancing performance according to users additional needs.