System Life Cycle
Stages of system analysis : analysis / design / development and
testing / implementation / documentation / evaluation.
Analysis stage ( researching in existing system ) : it can be through
Observation / Questionnaires / Interviews / looking at existing
system
Data flow diagram DFD : showing the data flows input and output
requirements, processing and type of data storage needed / user
requirement from the new system / suitable hardware and
software.
Design stage : design a new system based on the information
from analysis system.
Data capture form : paper based form or screen form must
include | clear heading / instruction / text box to collect
information ( name – date of birth – gender … ) , tick box to keep
choice easier, clear font, sufficient space or each filed).
On screen form should have: appropriate spacing between each
filed / not too much white space/ readable font / suitable font size
/ font color suitable with background color / drop down menu /
tick box / radio buttons / no overlapping / navigation buttons /
save & close buttons ( may in exam asking to evaluate form design
or create simple design ).
When you create database you should consider: data type /
tables and relationships / fields and its keys (Text – Numeric –
Boolean – Date & time - object…
Screen output ( report ) : output fields should be correct /
instruction is clear / avoid white space without nothing / suitable
font style and color / report should have (header – footer - Title )
and fitting page correctly.
Flow chart : show data flow through the system and how the
decision is taken / analyst used this chart to proposed overall the
system
Verification : a way of preventing errors when data is copied from
one medium to another
1. Double entry : data is entered twice / two people enter the
data / then compared
2. Visual check : same person is entering the data and
compare with the original document
Validation: Is a process where data is checked to see if it
satisfies certain criteria when input into a computer:
Range check : if data within acceptable value
Lookup check : if data entered exists and stored in a table of
data
Length check : if the data contains the required number of
character
Character type check : if data doesn’t contain invalid
characters
Format / Picture check : if the data in specific format
Presence check : if the data already present
Consistency check : if the fields correspond with each other
Digit check : an extra digits added
File structure : analyst should consider Field type / suitable
field name / data type
Design and testing strategy plan : Make sure ( that meets the
clients requirements / produce required output ) and Remove
any bugs
Developing stage : system should be created and fully tested
after design stage / during development file structure should
be created ( data type / field names ) / check validation rules /
create user interface.
Testing strategy: software creates as a modules (small parts)
each module should be tested / to make sure each part
working correctly.
Category of user testing : Normal / Abnormal / Extreme / Live
o Normal : data is acceptable /reasonable
o Extreme: data at the limits of acceptability
o Abnormal: data outside the limits of acceptability
o Live : new system output compared with existing system
output.
Implementation stage: change over from old system to new
system by
4 common methods :
Direct : Old system stopped overnight / replaced with new
system immediately ( immediate benefits / reduce cost / but
may be disaster
Parallel : two systems running side by side until new system
take over ( old system working in case new system filed – train
staff gradually / but more expensive / Time consuming.
Pilot : The new system introduced in one part of company
before whole company ( if failed only one part affected / train
staff in one area / less cost / but take time to implement.
Phased : Only one part from the system introduce for all fully
check the system / but more expensive / time consuming
Documentation : produce user documentation ( for end user )
and technical documentation ( for developers / programmers
User documentation: include.. how to ( load/ save / install / run
/search / query / sort / print out / add / delete )- purpose from
the system / hardware and software requirements / Error
handling / trouble shooting guide / log-in and out / error
messages meaning / glossary of terms / limitation of the
system / sample run with result.
Technical documentation: include.. program coding and listing
/ computer language used / program and system flowchart
/purpose from the system / limitation of the system / input
formats / hardware and software requirements / known bugs of
the system / list of variables / file structure / sample run with
result / output format / validation rules / error messages and it
meaning.
Evaluation : evaluate the implemented system to see if the
system resolved the issues
The main evaluation points : Compare final solution with the
requirements / Identify any limitations or necessary
improvements needs / Evaluate the user’s responses /
Compare results and performance for new system with old
system / Interview users to gather responses about new
system / questionnaires to gather responses.
Results from evaluation : ƒ Update Hardware: user feedback /
new hardware in the market / changes in the company ƒ
Update software : changes in the company structure / changes
in legalization.