chapter 7 Flashcards
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
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.
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.
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
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
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.
advantages of examining existing documents [2]
» Can see details of inputs and outputs
» Can understand the flow of data
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
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
what does DFD stand for
Data FLow Diagram
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.
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
what are two ways of having a system software
1) off the self software
2) bespoke software (specially written software)
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
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).
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
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
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
give example of alphanumeric datatype
A345FF or
07432011122
alpha characters (letters
or text) and numeric data (numbers)
give example of charecter datatype
X or d
a sinlge letter or text
give example of string datatype
example_of_text_
string
string of letters or numbers or other
symbols
types of numeric data
integer
decimal/real
currency
date/time
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.
What can validation check (just 2 examples)
a) data is in right type and format
b) within range of possible values
describe type check
data is of correct type
ex Letter “A” would not be allowed in a numeric feild
describe length check
contains a set of characters
ex candidate number should be 4 digits long.
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.
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
describe prescence check
existence check
describe lookup check
checks that data is one of the possible items in a list
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
