Iterative Development Phases (SQA National 5 Computing Science): Revision Note

Iterative development process

What is the iterative development process?

• The iterative development process is a structured cycle of stages used to create software

• Each phase is revisited as needed to improve the solution until it meets its purpose

• The six stages are:

  • Analysis

  • Design

  • Implementation

  • Testing

  • Documentation

  • Evaluation

Analysis

• The purpose of the analysis phase is to clearly understand the problem the program will solve

• You identify the inputs, processes, and outputs needed to meet the program’s goals

• Abstraction is used to remove unnecessary details and focus on what matters most

• This helps define the core functionality and requirements of the solution

Example

• In a train journey planner, you only need to know the route from stop A to stop B, not the full map layout

• A requirements list or document can include success criteria to check when each goal has been achieved

Design

• The design phase creates a blueprint for the program before coding begins

• Design tools can include:

  • Structure diagrams

  • Flowcharts

  • Pseudocode

• The design must show the program logic clearly so that implementation is straightforward

Implementation

• Also known as coding, this is where the program is built using a programming language

• Developers create the program in modules that work together to solve the problem

• Iterative testing happens during this stage to check that each module works correctly before combining them

Testing

• The program is tested to make sure it performs as expected and matches the original requirements

• Different types of test data are used to check for errors:

  • Normal data – valid input that should be accepted

  • Extreme data – valid but at the limits of acceptable input

  • Exceptional data – invalid input that should be rejected

• Testing confirms that the program works correctly and handles errors safely

Documentation

• Documentation explains how the program works and how it can be used

• It helps future developers and users understand the program

• Examples of documentation include:

  • User guides

  • Technical notes

  • Comments within the code to explain purpose and logic

Evaluation

• The evaluation phase assesses how well the finished program meets its intended purpose

• You consider:

  • Fitness for purpose – does it meet the user’s requirements?

  • Efficiency – are coding constructs used effectively?

  • Robustness – does it cope with unexpected inputs or errors?

  • Readability – is the code clear and well formatted?