Order of creating a new Computer System
- Analysis
- Design
- Development and Testing
- Implementation
- Documentation
- Evaluation
Analysis
- Researching the existing system
- Recording information about the current system
- System Specification
Methods of researching the existing system
- Questionnaires
- Interviews
- Observations
- Examination of existing documents
Questionnaires
Prepared questions are given to users of the system and they are left with the user to complete. They focus on simple questions like yes or no answers.
Advantages of Questionnaires
- Questions are answered quickly
- Fairly cheap to carry out
- Answers are honest because they are annonymous.
Disadvatages of Questionnaires
- People often dont complete or return them.
- You can get incorrect data if they dont understand the question.
- It is hard to ask very technical or specific questions.
Interviews
They take place face to face and usually involve more detailed questions than questionnaires. The interviewer talks with different people at different levels of the business and they might be asked different questions.
Advantages of Interviews
- Questions can be explained if misunderstood.
- Complex questions can be asked.
- You get a full set of data because the person has no choice but to answer all the questions.
Disadvantages of Interviews
- They take more time to complete
- They are more expensive because employees are taken out of their work hours.
- Answers might not be honest because they dont remain annonymous.
Observations
A system analyst sits and watches someone using the current system, this way they can log and make notes about different facts.
Advantages of Observations
- Analyst can see exactly what the system fails in and what it does well.
- Not as expensive because employees arent taken from their work space.
Disadvantages of Observation
- Person being watched might feel uncomfortable and work different than normally.
Looking at the current system’s documentation
The system analyst looks through the paperwork for the current system which contains the information needed to implement the new system.
Paperwork includes technical documentation, payroll systems and list of stock items to be stored in the new system.
Advantages of looking at the current system’s documentation
- It can save time because there are copies of previous analysis.
- You see existing inputs, outputs and processing.
- The analyst can predict the size of the system needed by looking at the amount of data it will need to handle.
Disadvantagges of looking at the current system’s documentation
- Time consuming to look through all the paperwork
- The analyst needs to be paid for the time they spend looking at the documentation.
- Time is wasted if the documentation isnt relevant to the new system.
Recording and analysing information about the current system
- Inputs and outputs need to be identified and process the current system.
- Problems are identified.
- User inforamtion and requirements for the new system are needed.
System Specification
- Need to identify suitable hardware and software for the new system.
Design
Documents, files, forms/inputs, reports/outputs and validation are to be designed.
What to design in design phase
- Designs to solve any problems
- Data capture forms and screen layouts
- Report layouts and screen displays
- Validation routines
- Required data/file structures
Validation checks
- Range check
- Length check
- Character check
- Format check
- Limit check
- Presence check
- Consistency check
- Check digit
Range check
Checks if data is between acceptable values
Length check
Checks if data contains the required number of characters
Character check
Checks that the input data doesnt contain invalid character.
Format check
Checks that data is in a specific format
