4.1 Systems Analysis

By: Momina

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

1. Collecting informationMethods of collecting information

Examination of Documents

Interviews

Observation

Questionnaires

Choice of MethodAnalysis Contents

Examination of documents 1. This helps the analyst identify the inputs and outputs of the system as it

currently operates2. 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 documentsThis 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

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Collecting Information Contents

Questionnaires

When using a questionnaire, keep in mind that the way the question is asked can influence the way people

answer the question.

Example of a questionPoor Question Better QuestionWhat details of the workers and their pay would you like to see on your workers’ payslips?

Which of the following information would you like to see on a workers payslip: worker’s nameWorker’s numberRate of payHours workedIncome tax rateIncome tax paidAny other information

Produces more precise information

Advantages and Disadvantages

Analysis Contents

Collecting Information Contents

Questionnaires

Advantages Disadvantages

An effective questionnaire once created allows you to give out many copies.

They may take a lot of time to produce

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.

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Collecting Information Contents

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 move away from the ‘script’.

It takes a lot of time to organise an interviewInterviewees 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.

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Collecting Information Contents

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 process

“Hawthorne Effect”- some people know 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.

Analysis Contents

Collecting Information Contents

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 situationExample: 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?

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Collecting Information Contents

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.

Analysis Contents

Collecting Information Contents

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 • Inputs • Outputs • Processing is required

Payroll Example:Input: details of the workersProcessing: calculation of the payrollOutput: payslips

Analysis Contents

3. Recording Information about the Current System

What are data flow diagrams?They are a graphical method of recording the inputs,

outputs and processing that have been identified.

“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.

Data Flow Diagrams System Flow ChartAnalysis Contents

Data flow diagramsThey consist of 4 components:i. Terminators (entity) ii. Processesiii. Flow arrowsiv. 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.

For Example:

Analysis Contents

For Example

Customers

Process order

Orders

Invoices

Orders

Rejected orders

Data Invoice

Order Information

Customer sends in order to the company

The on going process:

It is checked to see if it has all the required

information including customer name & address

If it does not, the order is rejected and sent back to

the customer.

If it does, the order is processed. The order information is printed

and filed.

An invoice is generated and filed ready to send to

the customer.

Analysis Contents

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

Process Order

Invoice Rejected Orders Orders

Key: Input

Process

Output Documentation

Magnetic Disk

Analysis Contents

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.

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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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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 Contents