Tuesday, March 12, 2013

Steps in Systems Analysis and Design

Steps in Systems Analysis and Design

Steps in Systems Analysis and Design

In business and industry new systems are produced by a person called a systems analyst or a

systems consultant

The analyst's task consists of three main parts:

1 Analysis- finding out what the present situation is.

2 Design-working out a new system.

3 Implementation-creating the new system and getting it into working order.

ANALYSIS

Defining the problem

It is necessary to set out very clearly the problem to be solved. What is wrong with the present system? What will the new system be expected to do?

Analysing the present system

The people involved are used to the present system so it is important for the analyst to understand it. In some cases there will be a good manual system which can be improved by the use of computers. It will be necessary to:

1 Observe the present system in use.

2 Interview the people who work with it.

3 Read any existing documents which explain how the system should work.

4 Work out the requirements of the system in terms of input, output, files, etc.

DESIGN

Feasibility study

Following the analysis of the present system the analyst will produce a feasibility report.

This is an investigation into whether a new system is realistic. It will enable the people requiring the new system to decide whether to go ahead with it.

It will:

1 Propose the outline for a new system (possibly with alternatives).

2 Summarize the costs and the benefits of this proposal. This summary will consider money, manpower, equipment and software.

Detailed design

This is the stage at which all parts of the new system must be thought out. (These parts are

listed as items (1) to (7) under computerized information processing systems in ).

Particular attention is given to:

1 Structure, organization and security of data files

2 Human considerations.

The new system should make good use of the skills of existing employees. The new system should be 'user friendly':

(a) Manuals should be simple and clear. They should be easy to use for reference.

(b) Computer programs should be easy to use. They should not irritate users by printing out too few instructions and headings, or too many.

(c) If a user enters the wrong data it should be easy to recover the situation and correct the data.

3 Whether it is necessary to purchase new hardware. The possibilities are:

(a) Buy a new computer system for the new application.

(b) Improve the existing computer system to cope, or possibly manage with existing hardware.

(c) Use the services of a computer bureau. A computer bureau is a firm which sells or hires out computer services. It has its own computing equipment and staff. Facilities offered may include:

(i) Software-the bureau may write software or make available program packages bought from elsewhere. The cost of this type of service is often shared by a group of firms all with the same requirements.

(ii) Computer time-the bureau may provide a batch processing service and may prepare the data for users. It may run a multi-access service for users with terminals for batch processing and multi-access systems).

(iii) Expertise- a bureau usually provides an advisory service.

4 Whether computer programs should be specially written or whether existing software should be bought.

(a) It is very expensive to have programs written specially.

(b) An existing software package may not exactly fit the user's situation.

IMPLEMENTATION

1 Purchase of new equipment if necessary.

2 Development or purchase of suitable programs.

3 Testing of the new system.

4 Documentation of the new system.

5 Staff retraining.

6 Gradual introduction of the new system. This may be carried out by running the old system and the new system together in parallel for some time. The advantage of this is that if the new system gets into difficulties, the old system is still running. The disadvantage is that the users have to work harder to keep both systems going at once.

7 Maintenance- the new system has to be monitored and problems solved as they arise.

RELEVANCE TO COMPUTER STUDIES COURSEWORK

The above account deals mainly with the solving of commercial problems. However, many of the same principles apply to Computer Studies coursework.

Assessment Objective B of the National Criteria for GCSE Computer Studies says:

'The candidates should be able to use computers sensibly to produce solutions to appropriate problems and be able to document their solutions. This includes the design of a simple system.

1 In using a computer to solve a problem it is a mistake to spend most of the time on program writing. A large amount of time needs to be devoted to:

(a) Getting the problem clear. The system you design is to solve a problem for a user. What

does that user want from it?

(b) Designing a complete system-not just a program.

(c) Designing the system to be robust and user friendly.

(d) Testing.

(e) Documentation.

2 Consider carefully whether a new program is needed at all.

Perhaps the problem can be solved by using a program that your school already has or can acquire, for example:

(a) File processing problems can often be solved using a database package

(b) Producing tables of figures on the screen can be done with a spreadsheet program .

Most examining boards are quite happy for candidates to produce as a project a solution to a problem which uses existing software .