Analysis : Requirements Specification

If it is decided that a new information system should be developed then it will be necessary to decide what the system will do. The requirements specification sets out what the new system will do. It will guide the development of the entire project.

• For a GCSE project the requirements specification will be used at the end of the project. An evaluation will be written to describe how well the new system carries out the tasks that were identified in the requirements specification.
• For a commercial project the requirements specification may form part of the contract between the software company and the people the system is being developed for. The software company will not get paid until the system operates as set out in the requirements specification.

A separate requirements specification should be produced for each task that has been identified. Each requirements specification should deal with :

Introduction
Outputs
Inputs
Desired Outcomes
Alternative Methods

The information you should include in each section is outlined below. A good analysis will discuss why things are being done and justify them.

Introduction

For each task you need a separate introduction. Whoever assesses your work will not be familiar with the problem that you are tackling and so you should include as much material as possible here. If the assessor does not understand exactly what the task you are tackling is then you are unlikely to gain good marks for the rest of the task.

Outputs

An output is a piece of information produced by an information system. Under the outputs section you should explain what you want the system to tell you. Typical outputs might include :

• The questions you want a database to answer using queries.
• The information that you want a spreadsheet to calculate.
• Any printouts you are going to produce with a DTP / graphics / word processor package.

You should explain what each output is and, if possible, why it is required.

Inputs

An input is a piece of information that is typed into an information system. Based upon the outputs that you want to produce you should be able to decide what information you will need to put into the computer system. This could be :

• Information that will be stored in database records.
• The information that a spreadsheet will require to perform calculations.
• Where you will obtain text/pictures from for publications, and what information must be contained in the publications.

Desired Outcomes

When you have completed the task you must produce an evaluation of your work. In the evaluation you need to assess the work you have done and compare it to what you hoped to achieve. The results you hope to achieve are known as desired outcomes or performance criteria. To produce a good evaluation you must compare what you have achieved directly to a set of desired outcomes that you produce now. It is therefore vital that you set your desired outcomes out clearly.

The first desired outcomes will be that the outputs you want to obtain are produced correctly. After this desired outcomes should include any other properties that you would like your system to have. Other possible desired outcomes include :

• Outputs / inputs should be presented in a particular way. e.g. to include a particular logo or to match a particular layout which you have specified.
• Validation should be performed on inputs.
• The task should achieve a particular effect, e.g. attract people to an event.

Desired outcomes should be clear and unambiguous. It is difficult to judge if unclear outcomes have been met.

Alternative Methods

This is the first point at which you should consider how you will complete the task. Under this heading you should consider possible methods that could be used to complete the task. You should compare the advantages and disadvantages of :

• A manual solution : E.g. producing a poster using paints or storing information in a card file system. You should outline a possible manual system if there is not an existing one.
• A computerised solution : At this stage you do not need to name the specific package you will use but can suggest some possible packages.

You need to explain why the computerised solution is most appropriate (if it isn’t choose a different task!).

GCSE ICT Companion 04 - (C) P Meakin 2004