7. The systems life cycle Flashcards
1
Q
What does the analysis look at?
A
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)
2
Q
What are the methods of researching an existing system?
A
Observation
Interviews
Questionnaires
Examination of existing documents
3
Q
Observation
A
An analyst observes somebody using the current system
4
Q
Advantages + disadvantages of observation
A
ads:
Can see exactly what is going well
disads:
Person might feel uncomfortable → work differently
5
Q
Interviews
A
Face to face, talks to people at various levels of the business, detailed questions
6
Q
Advantages + disadvantages of interviews
A
ads:
Questions can be explained
Questions can be changed to suit different people
disads:
Expensive to carry out
Takes longer
7
Q
Questionnaires
A
Prepared questions given to users, left to compete (paper/digital)
8
Q
Advantages + disadvantages of questionnaires
A
ads:
Questions can be answered quickly
Fairly cheap
disads:
Unclear questions cannot be explained
Incorrect data if people misunderstand
9
Q
Examination of existing documents
A
Looking at paperwork for current system
10
Q
Advantages + disadvantages of examining existing documents
A
ads:
Allows analyst to predict size of system needed
Can see existing inputs, processing and outputs
disads:
Time consuming
Expensive
11
Q
What is ‘requirements specification’?
A
Systems analysts specifies a list of requirements for new system
12
Q
What are ‘designs’ for?
A
the new system have a lot of thoughts put into them to try and reduce faults at a later stage.
13
Q
What are the things that are designed?
A
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)
14
Q
What are the four stages of development?
A
What are the four stages of development?
15
Q
What do validation checks/rules make sure of?
A
What do validation checks/rules make sure of?
16
Q
How are systems created?
A
System developed from lines of code (using code then creating interface)
17
Q
How are data structures tested?
A
Entering data that should be accepted
Purposely entering data that should not be accepted
18
Q
What are input methods?
A
A system that allows users to enter data into the system is known as data entry forms
18
Q
What are two types of system outputs?
A
On screen
Printouts (hard copies)
19
Q
How are system outputs created?
A
Report invoices
Pay slips
etc.
20
Q
Why is it important that testing takes place?
A
It must be tested to make sure that it works correctly
21
Q
Examples of modules that should be tested
A
Data structures - do tables hold data correctly?
Validation rules
Input screens
Output screens
22
Q
How to test for the whole system?
A
Make sure that all the individual modules work with each other correctly
23
Q
What is ‘normal data’?
A
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
24
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
25
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
26
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
27
What is ‘implementation’?
To install the system ready to use
28
Direct changover
Old system stops getting used one day, new system starts being used the next (very fast)
29
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
30
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)
31
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
32
Pilot running
New system piloted (trialled) in one part of business, if successful = introduced to all business/organisation
33
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
34
Phased implementation
New system introduced in phases (stages, or steps), gradually replacing parts of old system until new system has taken over
35
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
36
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
37
What is ‘technical documentation’?
Created for future developers of the system (explains how system was made)
38
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
39
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
40
Why is ‘user documentation’ needed?
Created for the benefit of anyone who is expected to use the system
41
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
42
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.
43
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
44
What are some of the final improvements?
Error correction
Add functionality
Performance improvement
45
who is a system analyst
a person who analyses systems.
46
state the 6 stages of the systems life cycle
analysis
design
development and testing
implementation
documentation
evaluation
47
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.
48
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
49
What are the stages of analysis ? [4]
Observation
Interviews
Questionnaires
Examination of Existing Documents `
50
describe observation
To watch daily work of personnel
Purpose to get a whole overview to see how the old system works
51
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
52
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
53
describe the interview stage
a one to-one question-and-answer session between the analyst and the user
54
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
55
advantages of interviews [4]
56
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
57
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.
58
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
59
describe the questionnaire
60
describe the questionnaire
distributing questionnaires to the workforce, clients or system users to find out their views of the existing system and to find out how some of the key tasks are carried out.
61
advantages of questionnaire [any4]
» The questions can be answered fairly quickly.
» It is a relatively inexpensive method (only need to produce questionnaires)
» Individuals can remain anonymous if they want (therefore give more truthful answers)
» Allows for a quick analysis of the data
» Interviewees can fill in questionnaire in their own time
» Allows a greater number of people to take part
62
disadvantages of questionnaires [any4]
» The number of returned questionnaires can be low; not always a popular method
» The questions are rather rigid because they have to be generic; it is not possible to ask follow-up questions
» No immediate way to clarify a vague answer to a question; it is not possible to expand their answers
» Users tend to exaggerate their responses as they are
anonymous
» Because anonymous, the interviewees may not take it seriously
63
describe the examination of existing documents method/stage
This method allows the analyst to see
1) how existing files are kept,
2) look at operating instructions
3) training manuals
4) check the accounts
This allows the analyst to get some idea of
1) the scale of the problem
2) memory
3) size requirements
4) type of input
5) output devices needed, etc.
64
advantages of examining existing documents [2]
» Can see details of inputs and outputs
» Can understand the flow of data
65
disadvantages of examining existing documents [2]
» Time consuming to go through the documents
» Expensive method as the analyst will have to spend time going through documents
66
why does analyst record and analyze information about the current system ?
» to Identify inputs, outputs and processing of the current system
» to Identify problems with the current system and improvements required
» to Identify the user and information required for the new system
67
what does DFD stand for
Data FLow Diagram
68
what are user requirements and their purpose ?
meaning - written by the analyst for the business in simple words (natural language , no jargon is used)
purpose -
» to enable customers to verify that the analyst’s proposal, based on investigations, aligns with the customer’s specifications.
» describe what the analyst thinks the customer does with their system.
69
what does system specification include
» identify and justify system hardware for the neww system
eg- input and output devices
» identify and justify system software for the new system
eg- operating system, storage, application software
70
what are two ways of having a system software
1) off the self software
2) bespoke software (specially written software)
71
off the shelf software
» Cheaper to purchase as there are no development costs
» More reliable as they only errors will have been located and tested
» Regular upgrades and improvements are more easily obtained
» More support as there are many users
72
Bespoke software(Specially written software)
[2adv 2disadv]
advantages -
» Meets cutomers needs as the software is specially designed for the customer
» Uses less memory as the software only has the feautres needed
» It is easier to use as less functions are there in the software
» Can be changed when the customer needs it changing
disadvantages -
» it will also require considerable training in using software unknown to the employees
» There will be no user base to seek help (they will have to rely on the software development technical team, which could be expensive).
73
Outline the main 4 process in the design stage
» File structures and data structures
» Input formats, including data capture forms
» Output formats, including screen layouts and report layouts
» Validation routines
74
A file is made up of a number of ———-, and each record is broken up into —————
A file is made up of a number of records, and each record is broken up into fields
75
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
76
One of the fields must be unique and will act as the ———— field – this is to allow each record to be uniquely identified
One of the fields must be unique and will act as the primary key field – this is to allow each record to be uniquely identified
77
give example of alphanumeric datatype
A345FF or
07432011122
alpha characters (letters
or text) and numeric data (numbers)
78
give example of charecter datatype
X or d
a sinlge letter or text
79
give example of string datatype
example_of_text_
string
string of letters or numbers or other
symbols
80
types of numeric data
integer
decimal/real
currency
date/time
81
define validation
validation is the checking that the data is sensible, reasonable or acceptable and to check if it follows a certain criterion. it is an automatic check carried by a computer.
82
What can validation check (just 2 examples)
a) data is in right type and format
b) within range of possible values
83
describe type check
data is of correct type
ex Letter “A” would not be allowed in a numeric feild
84
describe length check
contains a set of characters
ex candidate number should be 4 digits long.
85
decribe range check
to make sure numbers lie within a specified range (between an acceptable upper value and an acceptable lower value)
ex exam score would range from 1 to 100.
86
decribe format check
data may have a fixed pattern of number of digits and character.
ex a class should in the format of 10c
data - dd/mm/yyyy
87
describe prescence check
existence check
88
describe lookup check
checks that data is one of the possible items in a list
89
describe check digit
extra digit added to a number and calculated from it to make sure that the number is entered correctly to the computer.
e ISBN and barcode validation
90
What is validation?
Validation is check that is performed by the computer as the data is being entered into the system.
91
They will ensure that the data is:
Sensible, reasonable, within acceptable boundaries and complete.
92
What are the main categories of validation checks?
Range checks, type checks, presence, checks, length checks, lookup checks, picture checks and digit checks.
93
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
94
What are the main categories of validation checks?
Range checks, type checks, presence, checks, length checks, lookup checks, picture checks and digit checks.
95
What are range checks?
A range check sets an upper and lower boundary for the data. The data must lie between those two values.
96
What are type checks?
This makes sure that the data entered is of the correct type. e.g. Numeric, string, boolean and date/time.
97
What are presence checks?
(Also called existence checks). This checks that there is something filled in and will insist that a value is entered for that field.
98
What are length checks?
A single character has a length of 1. ‘Hello’ has a length of 5. A length check ensures that the date isn’t more than a set number of characters.
99
What are lookup checks?
A lookup check takes the value entered and compares it against list of values in a separate table.
100
What are picture checks? (Also called format checks or input masks)
Same data entries may be a combination of numbers and letters, so you cannot use a type check. But the location of letters and numbers may be the same each time: (BLTR36). This checks they are always in that format.
101
What is verification?
When you enter information from a piece of paper to a computer, you must verify it to make sure it is the same.
101
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
102
What is the source document?
103
What is the source document?
The paper based copy of your data is called the source document.
104
What is the object document?
The copy on the computer is called the object document.
105
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
105
What is verification?
When you enter information from a piece of paper to a computer, you must verify it to make sure it is the same.
106
How do your verify they are the same?
Verification is making sure that the information on the source document is the same as the information on the object document.
107
VERIFICATION:
Does NOT ensure that the information is correct, just that it has been copied correctly from the paper to the computer.
108
What are the two main methods of verification?
Double entry and manual verification.
109
What is double entry?
This is entering the data twice. The computer compares the two sets of data and informs the user if they are different. This happens when creating a new password.
110
What is manual verification?
This is proofreading the data. Just checking that it’s the same. Not very reliable due to human error.
111
What are the two main errors when entering data into a computer?
Transcription errors and transposition errors.
112
What are transcription errors?
Transcription errors are when you have made a mistake copying the data. So hitting a wrong key or hitting two keys at once.
113
What are transposition errors?
Transposition errors are when you have reversed two numbers or letters.
114
VALIDATION + VERIFICATION:
Don’t make sure the information is correct. Validation makes sure it is set to rules and verification makes sure it is the same as the source information.
115
What is verification?
When you enter information from a piece of paper to a computer, you must verify it to make sure it is the same.
115
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
116
What does encoded do?
Simplifies the way data is represented
116
Can data be encoded
Yes
116
Give an Example of Encoded
M- Male and F- Female
116
What are the Benefits of encoded Data
Less computer memory used
It is faster to enter the data
Fewer errors made when data is entered
Validation of the data is easier
116
What is it call for the time taken for a computer to find an item of data?
Speed of Access
116
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
116
Where does the memory come from?
116
What is verification?
When you enter information from a piece of paper to a computer, you must verify it to make sure it is the same.
116
Where does the memory come from?
Random Access Memory (RAM)
116
What is the access time measure in?
Nanoseconds
117
The access time for hard drives and other secondary data is…
Milliseconds
118
What does Speed of Access mean?
The time taken from the time the request for data is made to the time that the data is received
119
What are the advantages for using ICT for storing data?
Data can be edited easily
Data can be encrypted so that it is secure
Back-up copies can be creates easily
Data can be transmitted very quickly to another device
120
What are the Disadvantages if using ICT for storing data?
Cost of equipment can be high
- Viruses or hackers may damage the data
121
Data is only useful if…
Valid
Sensible
Up-to-date
122
What is data Validation used for?
Make sure that the data being entered is sensible
123
What is Data Verification used for?
Ensure that the data being entered has been entered correctly
124
What is verification?
When you enter information from a piece of paper to a computer, you must verify it to make sure it is the same.
125
Data can be…
Copied from one medium to another (Transcribed)
Sent from one computer medium to another (Transmitted)
126
What are input methods?
A system that allows users to enter data into the system is known as data entry forms
127
Verification checks are needed to…
make sure the data received is the same as the data that was sent
128
How are transcription errors caused?
Corruption of data by electrical interference
129
Give 3 transcription errors
Omission - Leaving out data
Transposition - e.g. typing 1324 instead of 1234
Spelling mistakes
130
Give 3 Methods of Verification
Visual Check
Double Keying
Parity Check
131
What is Parity Check?
As a series of binary numbers.
Even Parity - Total number of 1’s are Even
Odd Parity - Total number of 1’s are Odd
132
Name four types of validation check?
Range Checks
Presence Checks
Format Checks
Check Digits
133
What are the two new Validation Checks?
Batch Total - Check the total at start then checks at end if different this means an error in transmission
Hash Total - Is a batch total that has no meaning.
