Unit 11 - Systems Analysis P1 P2 P3 M1

The Systems Life Cycle

P1 – Outline principles of system analysis

There are multiple definitions of what systems analysis is but most include three basic principles. These three principles include (1) the studying of the system already in place, (2) specifying the requirements and (3) designing and implementing new systems.

Systems analysis is a process that has many ways of being fulfilled depending on the company but the key purpose is the same and it should always be structured and organised.

Role of Systems Analyst

The role of a systems analyst has a job to process data requirements on an organisation as well as deciding on whether computerisation should be introduced or if there is already a computer system in place they would decide whether any modification is needed to it. Further to this a systems analyst would specify how any new system would work, check what the hardware and software requirements would be and implement the new system and ensure it works efficiently.

A systems analyst would need a need an understanding of the organisation and a knowledge of how computers are used. Other skills they need are being an excellent communicator, being able to extract information as needed about the current system and doing this without alienating people in the user departments.

P2 – The stages of a development life cycle

Rapid Application Model

Rapid Application Model

The Rapid Application Method is often preferred as uses iterative development which involves the repeating of the processes until they are fulfilled. The benefits of using this life cycle model is that the development is fast and it gives opportunity to refine the system throughout.

 

 

1.       Analysis. The first stage in the systems life cycle is to analyse the problem. This is done by writing a ‘Terms of Reference’ document which contains information on what the problem is and the definition of the problem. An initial investigation determines whether any further investigation is needed.

More detailed systems analysis then follows which involves studying the current system, if there is one on place, and also proposing solutions to any problems. The analysts may be asked to prepare a feasibility study and a cost/benefit analysis. The analyst will present a written report to user and information systems management who will consider alternatives and resources such as time, money and organisation. A decision is then made as to whether to the project will proceed or not.

2.       Design. This stage involves the designing of the inputs, outputs, system controls, test plan and potentially a database. All aspects of the design are documented and the input/ output forms are designed along with the clerical procedures.

3.       Development. The development stage is split into two aspects, program development and equipment acquisition. Program specifications will be designed by either the systems analyst himself or by a senior programmer and programmers will the code the program and test and document the programs.

4.       Implementation. In this stage the new system becomes operational therefore it is a critical phase and requires timing and coordination as well as training of all the user departments.                                       

5.       Maintenance. During the maintenance phase the systems are monitored for their performance and modifications are made in case of errors, bugs or glitches. Documentation is kept up to date.

Waterfall Model

The waterfall model is an alternative to the Rapid Applications Development model. Unlike the standard systems life cycle it does not go in a complete cycle; instead it continues in a linear sequence and like a waterfall it doesn’t go back to the top.

The benefits of the waterfall model are that it is simple, sequential and the processes move from one step to the next with no repeated steps.

Because it does not allow for this continuous cycle the steps will not be revisited so there is no revision however if the steps are completed thoroughly then the waterfall method can be effective.

Spiral Model

The spiral model is very similar to the waterfall method in that it does not go in a complete cycle and has a start and a finish, however this model also includes prototyping within it the same as the RAD model. The spiral models is generally used for more large scale projects with the main advantage of it being that it is able to cope with more change and also cost estimates are fairly reliable.

P3 – The benefits of structured analysis

Each of the three methods mentioned above have different benefits associated with them. Here is a list of the benefits for each of the different models.

Rapid Application

·         Development is quicker with the RA model

·         This model allows for refinement and improvements during the design

Waterfall

·         The waterfall model is easy to understand and follow due to its linear sequence

·         Each of the processes is in a different section allowing for good  control

·         There are no repeated steps; the method goes from one step to the next

·         The  waterfall method gives accurate deadlines which should be met

Spiral

·         The spiral model is able to cope with changes

·         Cost estimates are fairly accurate

M1 – Appropriate uses of different developmental life cycle models

“You have been contacted by the tutor of your assistant and asked to participate in a teaching session. Prepare some background notes for a proposed tutorial discussion meeting with your assistant, his tutor and the rest of the class. The title of the seminar is ‘Appropriate uses of different developmental life cycle models’. Rehearse the discussion with someone else, possibly you tutor, and record it or document it in some other way.”

Background Notes

 

The two most common life cycles are the waterfall and spiral model, both are good but each is suited to different situations

Appropriate uses of Waterfall model:

This is the most commonly used life cycle model, it is simplistic and follows a set procedure with each stage being completed one at a time.

This model is better suited for smaller businesses and smaller projects that have clear requirements and specific end results which are used to determine if the project has been on completed on time and to standard. With larger projects the scope can change and so this model is not suited to those types of projects.

Appropriate uses of Spiral model:

Unlike the waterfall the spiral model has just four stages, these are: Planning, Risk Analysis, Engineering and Evaluation and each stage can be repeated and returned to multiple times allowing it to build upon the baseline spiral.

The first stage is the planning which allows for gathering of the requirements. The second stage is the risk analysis which weighs up the risks and benefits. The engineering stage involves producing the software and systems and implementing them and finally the Evaluation stage involves gaining the feedback from the customer and if changes are needed the spiral can start again, this may happen a few times.

The spiral model is better for larger projects as it analyses risks early on, which can identify problems early on which helps to produce a better system. It is also better suited to larger products which have larger budgets allowing all the sections of the spiral model to be utilised.