7. The systems life cycle Flashcards
What does the analysis look at?
Current problems
Problem to be solved by new system
What does the user want
Identify inputs, processing and outputs
User and information requirements of new system (what tasks it should be able to do)
What are the methods of researching an existing system?
Observation
Interviews
Questionnaires
Examination of existing documents
Observation
An analyst observes somebody using the current system
Advantages + disadvantages of observation
ads:
Can see exactly what is going well
disads:
Person might feel uncomfortable → work differently
Interviews
Face to face, talks to people at various levels of the business, detailed questions
Advantages + disadvantages of interviews
ads:
Questions can be explained
Questions can be changed to suit different people
disads:
Expensive to carry out
Takes longer
Questionnaires
Prepared questions given to users, left to compete (paper/digital)
Advantages + disadvantages of questionnaires
ads:
Questions can be answered quickly
Fairly cheap
disads:
Unclear questions cannot be explained
Incorrect data if people misunderstand
Examination of existing documents
Looking at paperwork for current system
Advantages + disadvantages of examining existing documents
ads:
Allows analyst to predict size of system needed
Can see existing inputs, processing and outputs
disads:
Time consuming
Expensive
What is ‘requirements specification’?
Systems analysts specifies a list of requirements for new system
What are ‘designs’ for?
the new system have a lot of thoughts put into them to try and reduce faults at a later stage.
What are the things that are designed?
Data entry screens (how data can be entered in system (e.g text boxes, drop menus)
User-interface layouts (what will things - menus, searching look like
Printed outputs (what will printed outputs look like)
Screen-based outputs (what will outputs on screen look like)
Structures to store data (e.g. for databases, how table will be designed)
Data validation methods (how will system prevent incorrect data from being entered)
Data verification methods (How will system check data entered is correct)
What are the four stages of development?
What are the four stages of development?
What do validation checks/rules make sure of?
What do validation checks/rules make sure of?
How are systems created?
System developed from lines of code (using code then creating interface)
How are data structures tested?
Entering data that should be accepted
Purposely entering data that should not be accepted
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
What are two types of system outputs?
On screen
Printouts (hard copies)
How are system outputs created?
Report invoices
Pay slips
etc.
Why is it important that testing takes place?
It must be tested to make sure that it works correctly
Examples of modules that should be tested
Data structures - do tables hold data correctly?
Validation rules
Input screens
Output screens
How to test for the whole system?
Make sure that all the individual modules work with each other correctly
What is ‘normal data’?
data which should be accepted and pass the test without any problems (in this example any numbers between 1 and 5)
E.g. the numbers 1,2,3,4, or 5 should be accepted
What is ‘extreme data’?
data on the border of what the system will accept
E.g. In the same scenario, 1 or 5 would be used to test the borderline data
What is ‘abnormal data’?
Data that should not be accepted by the system
E.g. data anything than 1,2,3,4,5 should be tested
What is ‘live data’?
data that is actually used by the company’s customer
All modules would be tested with real-life data that the company actually uses
What is ‘implementation’?
To install the system ready to use
Direct changover
Old system stops getting used one day, new system starts being used the next (very fast)
Advantages + disadvantages of direct changover
ads:
Takes minimal time and effort
Can be used immediately
disads:
New system fails, no backup system, data lost
Staff have to be trained to use new system before installed
Parallel running
Old system + new system run alongside each other for period of time (data input into both old + new producing two sets of results)
Advantages + disadvantages of parallel running
ads:
If anything wrong with new system, old system = backup
Outputs can be compared to see if new system is running correctly
disads:
Takes a lot of time and effort
Pilot running
New system piloted (trialled) in one part of business, if successful = introduced to all business/organisation
Advantages + disadvantages of pilot running
ads:
All features can be fully tested
Something goes wrong, only small part of organisation is affected
Staff who were part of pilot scheme can teach other staff
disads:
For the department doing the the pilot, there’s no backup
Phased implementation
New system introduced in phases (stages, or steps), gradually replacing parts of old system until new system has taken over
Advantages + disadvantages of phased implementation
ads:
Allows users to gradually get used to the new system
Staff training can be done in stages
disads:
If systems is broken or crashes, no back up
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
What is ‘technical documentation’?
Created for future developers of the system (explains how system was made)
What is included in technical documentation?
Purpose of system (problem that system solves)
Hardware requirements (hardware needed to run system - e.g. processor speeds
Software requirements
Memory (RAM) requirements (lowest + recommended amount of RAM needed to run system
Copies of all system designs (designs for input screens and outputs screens described)
Copies of system flow charts (how data will flow through new system)
Explanations of file structures (tables) used - table’s field names, data types, etc.
Programming language used to code the system (make it easier to hire people in future)
Listings of the code (how code joins together + annotations that explain what code does)
Details of system bugs
User interface designs
Input formats - kind of data system accepts
Output formats - what kind of data system produces
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
Why is ‘user documentation’ needed?
Created for the benefit of anyone who is expected to use the system
What is included in user documentation?
The purpose of the system - what the system can be used for
Limitations of the system
Hardware requirements - listing of hardware user needs to run the system
Operating system required - which operating systems can be used to run the system (Windows, MAC OS etc.)
How to open load the system
How to login and logout of system
How to search for system data
How to input new data
How to amend data
How to sort data
How to save files
How to print files
How to handle system errors/meaning of error messages
Frequently asked questions (FAQs)
Troubleshooting guides - how to identify what has gone wrong, what can be done
Help guides/Tutorials - help user to learn how to use the main features of system
Glossary of terms
Why is it important to evaluate a system?
see if the system is doing the job it was designed to do.
see if the system is working well with minimum errors.
see if the staffs can use the system properly.
How is an evaluation carried out?
Comparing the system against the initial requirements
Evaluating user’s experiences
Identifying limitations of the new system
Identifying system improvements
What are some of the final improvements?
Error correction
Add functionality
Performance improvement
who is a system analyst
a person who analyses systems.
state the 6 stages of the systems life cycle
analysis
design
development and testing
implementation
documentation
evaluation
why would a company update its current system
the existing computer equipment cannot be repaired
Changes to laws or taxes requiring radical overhaul of software.
» More suitable hardware is now available to improve efficiency and reliability.
» There is a need to expand the company.
describe what happens during the analysis stage [any4]
» Research the current system
» Identification of input and output
» What processing takes place?
» Problems with the current system
» User requirements for the new system
» What are the information requirements?
» Identify hardware and software for the new system
What are the stages of analysis ? [4]
Observation
Interviews
Questionnaires
Examination of Existing Documents `
describe observation
To watch daily work of personnel
Purpose to get a whole overview to see how the old system works
advantages of observation
» it is possible to get an overall view of the system
» inexpensive method as the analyst is only watching the workers
» the analyst obtains reliable data
disadvantages of observation [2]
» People are generally uncomfortable being watched and may work differently
» People who violate the rules will not do that if they know they are being watched
describe the interview stage
a one to-one question-and-answer session between the analyst and the user
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
advantages of interviews [4]
advantages of interviews [4]
» Questions can be explained or repeated
» Can change questions in light of previous answers
» The user is more open and honest with the answer
» Interviewer can detect body language and facial expressions
disadvantages of interviews [any4]
» Time consuming to interview all the users as the interviews are carried out one at a time [2]
» The interviewee may be dishonest with the questioning as it is not anonymous [2]
» Expensive due to analyst’s time [1]
» Workers may not be available at the time the analyst is available.