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 system
2. Description of current system
3. Identifying problems with current system
4. Identifying and agreeing to customer’s
requirements.
5. Interpreting customers requirements.
6. Producing cost benefit analysis
7. Producing data flow diagram
This is also known as a Feasibility Study.
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Feasibility Study
Description of existing system
Description of
existing system Description of
existing system
Description 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 data
1-normal-data is acceptable
2- extreme- data is at the limits
3-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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Documentation
User 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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System analysis

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