system life cycle

• If a current system is not performing to expectations, an external review can be done to develop a new system that is more fit for purpose
• System analysis

  1. Review existing system

  2. Collect information

  3. Identify problems
• System design

  Design a new system to correct problems and limitations identified in analysis
• System development and testing

  Develop and test the new system
• System implementation

  Replace old system with new system
• User documentation

  Documentation for people using the system
• Technical documentation

  Documentation for people maintaining the system
• System evaluation

  Evaluate if new system is meeting requirements
• If new system is not meeting requirements, can review the analysis, design, development and implementation stages again
• Analysis

  • Collect information about present system
  • Identify problems
• Observation

  Get an external, unbiased view of the current system
• Interviews

  Ask open-ended questions to get feedback
• Questionnaires

  Reach a larger audience to gather feedback
• Collecting documents

  Analyze existing documentation to identify inputs and outputs
• The systems life cycle includes analysis, design, development, implementation, documentation and evaluation stages
• When creating a new system, the system analysis researches the existing system and identifies problems and requirements for the new system
• The requirement specification outlines the expected improvements and expectations for the new system
• Design

  • Determine the data that needs to be captured
  • Consider data types and relationships
  • Decide on paper-based or electronic forms
• Data validation

  Checks if entered data fulfills specific criteria to ensure validity
• Presence check


  Checking if data is present in a field before allowing the user to proceed
• Range check

  Checking if a value is within an acceptable range
• Range checks

  • Checking a date is within a specific month
  • Checking a year is between 7 and 12 or 13
  • Checking a test score is between 0 and 30
• Length check

  Checking if the length of an entered value is within an acceptable range
• Length checks

  • Checking a student candidate number has the correct length
  • Checking a phone number has the correct length
• Type check

  Checking if the correct data type has been entered (e.g. only numbers, only letters)
• Format check

  Checking if data has been entered in the correct format (e.g. date in DD/MM/YYYY format)
• Check digit

  A digit calculated from other values and added to the end of a code to verify its accuracy
• Data verification

  Double checking entered data to ensure it is correct
• Data verification methods

  • Proofreading
  • Double entry (e.g. entering a password twice)
• Verification is needed to check data that has passed validation but may still contain errors
• Data entry form design

  • Appropriate spacing for each field
  • Screen is filled, not too much white space
  • Clearly defined input areas
  • Easy to read font and size
  • Sensible color and background
  • Use of dropdown menus and tick boxes
  • Navigation aids
• Phone number field is set as text rather than numeric to save file space as it will not be used for calculations
• Validation checks

  • Presence check
  • Length check
  • Range check
  • Type check
  • Format check
• Validation checks must be different for each field
• Data types

  • Health number: Numeric integer
  • Date of birth: Date
  • Gender: Boolean
  • Blood group: Text
• Examples referring to verification, validation or proofreading

  • Proofreading: Reading data without reference to original
  • Validation: Range check
  • Verification: Copying data from one medium to another
• The online booking form has positive aspects like clear labeling and enough space, but lacks instructions, navigation buttons and dropdown menus
• Gender field validation is limited to only accept M or F
• Encoding data (e.g. M/F for gender) reduces file size and chance of errors
• Online data entry form design

  • Suitable title
  • Enough space for each field
  • Navigation aids
  • Instructions for user