System analysis

System Analysis (Summary)

By:Momina

Introduction• System analysis team brought to review existing system +

suggest number of improvements.• Existing system either manual paper-based or computer-

based operation.Analysis/ Feasibility Study

Design

Development and Testing

Implementation

Documentation

Evaluation and Review

Analysis Stage

1. Collecting data from current system2. Description of current system3. Identifying problems with current system4. Identifying and agreeing to customer’s requirements.5. Interpreting customers requirements.6. Producing cost benefit analysis7. Producing data flow diagram

This is also known as a Feasibility Study.

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Feasibility StudyDescription of existing system

Description of existing system Description of

existing systemDescription of existing systemDescription of

existing system

•Objectives•Boundaries•Constraints

•Identify problems•Projected costs

•Essential requirements•Desirable Features

•Development plan•Cost-Benefit Analysis.

This can be done by:-questionnaires-Observations-Interviews-Paper-trail

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Design Stage

• Design data capture forms• Design screen layouts• Design output forms and reports • Producing system flowcharts/pseudo code• Selecting validation rules• Designing file structure and tables• Select hardware and software requirements.• Verifying and Validating data

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Verification

• This is a way of preventing errors when data is copied from one medium to another. Two common ways are:

1. Double entry: data is entered twice, using 2 different people. Computer then compares the entries and identifies any differences

2. Visual Check: checking for errors by comparing data entered on the screen with the original document. – NOT proofreading.

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Validation

• This is a process where the data is checked to see if it satisfies certain criteria when input into the computer, checking if it falls in accepted boundaries.

Validation check Description

Range Check Checks whether data is within acceptable or given values

Length Check Checks if the data contain s required number of characters.

Character/type check Checks that the data does not contain invalid characters.

Format/Picture check Checks that data is a specific format

Presence Check Checks if data is actually present and has not been missed out

Consistency Check Checks if fields correspond with each other

Check digit Looks at an extra digit which is calculated from the digits of a number and then put on the end of the number

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Development Stage

• File structure is finalised at this stage.

• This can then be created and then fully tested to make sure it is robust (not easily broken) when the system actually goes alive.

• Validation and verification are used to make sure that the correct data is stored in the files.

• This needs to be fully tested ensuring any unwanted data is stopped and that the transfer of data is accurate.

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Chosen hardware is now identified– how the screen will be used to collect data.

Testing Strategies

• There are two types of testing.1. formative testing – this is when you test the system as you go

along. Even if all individual parts are working normally, the whole system may not work properly when put together.

2. summative testing—this is when the entire system is tested as a whole after necessary amendments have been made.

• There are 3 types of data1-normal-data is acceptable2- extreme- data is at the limits3-abnormal-data that is outside the limits of acceptability.

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Implementation

Changeover Method Description Advantages and Disadvantages

Direct The old system is stopped overnight and the new system introduced immediately

Benefits are immediate Costs are reduced – only one system is used

there is no need to pay for two sets of staff Less likelihood of a malfunction since the

new system will have been fully tested. Method is disastrous if the new system

fails.

Parallel Running The old and new system are run side by side for a time before the new system takes over altogether

If new system fails, old system is still available as a back up

It is possible to train staff gradually Staff has time to get used to the new

system. Is more expensive than direct than direct

changeover, since extra staff is needed to run both systems.

Phased Implementation

Initially, only part of the new system is introduced. Only when it proves to work satisfactorily is the next part introduced, and so on, until the old system is fully replaced.

If the latest part fails – is only necessary to go back into the system to the point of failure

It is possible the ensure the system works properly before expanding

This is more expensive than direct changeover—it is necessary to evaluate each phase before moving on to the next stage.

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DocumentationUser Documentation- designed to help users to learn the software or system

Technical Documentation- designed to help programmers and analysts who need to make improvements to the system

-purpose of the system -purpose of the system

-how to log in/log out -program listing/coding

-how to load/run software -flowcharts/algorithm

-how to save files -input formats

-how to do a search -software/hardware requirements

-troubleshooting - Meaning of error messages

-print layouts -validation rules

-tutorials -list of variables used

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Evaluation• Compare the final solution with the original requirements.• Identify any limitations in the system• Compare the test results from the new system to the old system• Measure time taken to complete tasks.• Interview users to get response.Some changes may be necessary like:• New hardware in the market• Changes within the company requiring more hardware.• Modification of software.• Changes in legislations

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