2. What is involved in Systems
Analysis?
1. Collecting information on how the existing system works
2. Establishing its inputs, outputs and processing
3. Recording information (E.g. in the form of data flow diagrams)
4. Identifying problems
After completing those four:
5. Identify suitable hardware and software
6. Identify user and information requirements
3. 1. Collecting information
Methods of collecting information
Examination of Documents
Interviews
Observation
Questionnaires
Choice of Method
Analysis
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4. Examination of documents
1. This helps the analyst identify the inputs and outputs of the system as it
currently operates
2. Assess the processing that the computer system will need to carry out.
3. Calculate the number of documents that are processed
4. Volume of data on all the documents
This would help the analyst decide on the size of memory.
Input: the number of hours
worked, this is the new variable
each month
Output: figures that appear
on the payslip
Processing: using the input
and other stored figures to
perform calculations
Collecting Analysis
Information Contents Contents
5. Questionnaires
When using a questionnaire, keep in mind that the way
the question is asked can influence the way people
answer the question.
Produces more
Example of a question precise information
Poor Question Better Question
What details of the workers and Which of the following
their pay would you like to see information would you like to see
on your workers’ payslips? on a workers payslip:
worker’s name Advantages and
Worker’s number Disadvantages
Rate of pay
Hours worked
Income tax rate
Income tax paid Analysis
Collecting
Any other information Contents
Information Contents
6. Questionnaires
Advantages Disadvantages
An effective questionnaire once created They may take a lot of time to produce
allows you to give out many copies.
Since they are impersonal and
anonymous, workers might exaggerate
their answers
Difficult to ask further questions
Not all the employees will actually fill in
the questionnaire.
Collecting Analysis
Information Contents Contents
7. Interviews
• Takes time to complete an interview
• This technique is used with key personnel and
representatives of the workers.
Advantages Disadvantages
They are flexible; the interviewer can It takes a lot of time to organise an
move away from the ‘script’. interview
Interviewees may not give very accurate
answers ; they may try to provide the
interviewer with answers that they want to
hear.
It takes a lot of time to complete interviews.
Collecting Analysis
Information Contents Contents
8. Observation
• This is when a system analyst just watches all the
activities that are going on in the office.
For example: seeing how the data comes in about a
customer and how it is processed and used to produce an
invoice.
Advantages Disadvantages
The system analyst can see the whole “Hawthorne Effect”- some people know
process that they are being watched so they may
change the way they work.
A data flow diagram can be produced
which help determine the inputs, outputs
and processing.
Collecting Analysis
Information Contents Contents
9. Choice of Method
What does it depend on?
1- The type of information that is being collected.
2- The practicality of using the method in the situation
Example: If there were lots of employees it would take
very long to personally interview each one.
What will be most appropriate
to our case scenario?
Collecting Analysis
Information Contents Contents
10. Our Scenario
Peter & Irene interviewed as they are the owners of the
company; specific needs are established.
Two secretaries are observed as they both do different
aspects of work.
Sales people are busy all day so it would be easier to give
them a questionnaire. They would give them the opportunity
to fill out the questionnaire. This is much better than having a
rushed interview.
Van drivers will not be in the office most of the time so it
would to also give them questionnaires.
Collecting Analysis
Information Contents Contents
11. 2. Establishing inputs, outputs and
processing in the existing system
The analyst will use the information that they obtained
from examining the documents used in the current
system to produce documentation of the system.
This stage is usually done while producing a data flow
diagram
Each section of the system is examined to see what
specific Payroll Example:
• Inputs Input: details of the workers
Processing: calculation of the
• Outputs payroll
• Processing is required Output: payslips
Analysis
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12. 3. Recording Information about the
Current System
“It is important to keep accurate records of systems
analysis since the system will continually evolve and
other systems analysts and programmers will need to
develop the system even further.
What are data flow diagrams?
They are a graphical method of recording the inputs,
outputs and processing that have been identified.
Data Flow Diagrams System Flow Chart
Analysis
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13. Data flow diagrams
They consist of 4 components:
i. Terminators (entity)
ii. Processes
iii. Flow arrows
For Example:
iv. Stores (data store)
1. The order comes from the customer. The customer is no part of the process
so they are placed in the terminator.
2. Data from the customer is the order. This information is processed to
produce invoices. They are placed in the process box.
3. Output from the system (invoices and printed orders) are recorded for future
use. Despite the fact that information is not stored on computers, this
process can still be viewed as being stored. This data is called a store.
4. Data flow. These are the arrows. They show the direction of the data flow.
Analysis
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14. For Example
Customers Orders
Orders
Rejected
orders Process Order
order Information
The on going process:
It is checked toorder is
If it does, the see if it
IfAndoes not, the order is
it invoice is generated
Customerthe Thein order
processed. required
has all sends order
Data and filed and sent back to
rejected ready to send
Invoices information is printed
information including
to the company
Invoice the customer.
customer name & address
and filed.
Analysis
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15. System Flowchart
This is a method that can be used to design system solutions.
It is not frequently found in the analysis stage
A system flowchart is designed to represent a new
computerised system. The dataflow diagram represents the
old manual system
Customer
Orders Key: Input
Output
Documentation
Process Order Process
Magnetic
Rejected Disk
Invoice
Orders Orders
Analysis
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16. 4. Identifying Problems with the Current
System
Use of dataflow diagrams: helps analyst identify problems with
the current system.
• Weaknesses can be identified.
• If you show the process in great detail it will be easier to
identify if there are problems like job duplication or time
wasting.
For example (in our scenario)
It may be unnecessary to have both secretaries involved in entering data for the
payroll process. So in the new system these two files of information may be
linked together making the process easier.
Analysis
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17. 5. Identifying suitable hardware and software
for a new system
• Keep in mind that the actual hardware/software is not chosen
just yet.
• From the data flow diagrams the required outputs, storage and
process requirements have been decided. The analyst can then
make generalised recommendations for the software/hardware.
For example (in our scenario)
Daniel knows the volume of data being input from the terminators and flow
arrows. This can then allow him to determine an appropriate method of inputting
data into the system. He can give details on the size and speed of the processor
required. The stores in the dataflow diagram will allow Daniel to make predictions
on how much data needs to be stored allowing him to recommend the size and
number of storage devices. Analysis
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18. 6. Identifying the user and information
requirements
“ The process of collecting information about the existing system
will have been very important to see exactly what job each
worker is doing.”
For example (in our scenario)
Daniel has already interviewed Irene and Peter and will use this information to
discover their requirements for the new system. Using his own observations and
the data flow diagram he can make generalised user requirements. This will then
allow Daniel to produce a requirements specification. This is a list of features of
the system that are required. These will be things that the user wants to be able
to do with the system. For instance:
-“I want the system to find me the details of an individual customer quickly.”
-“I want the system to produce the payroll overnight so I can just set it to print at
the end of one day and its there for me the next morning.” Analysis
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