Software Quality Assurance(SQA)

• • • McCall’s Quality Model is one of the earliest software quality models, proposed by Jim McCall in 1977.
    • McCall’s Quality Model provides a comprehensive, structured framework to evaluate software quality by dividing quality factors into product operation, revision, and transition.
    • It helps improve reliability, maintainability, and adaptability of software systems.
    • The model focuses on the relationship between software quality characteristics and product operations, revision, and transition.
    • Structure of McCall’s Quality Model

McCall’s model is divided into three major perspectives:-

• • • • Product Operation

These factors describe how well the software performs during operation and include features –

• • • • • • Correctness – It is the ability to meet specified requirements.
          • Reliability – It is the ability to perform consistently without failure.
          • Efficiency – It is the use of system resources effectively.
          • Integrity – It is the protection from unauthorized access (security).
          • Usability – It is the ease of use and user-friendliness.
      • Product Revision

These factors relate to the ability to modify the software and include –

• • • • • • Maintainability – It is the ease of fixing defects.
          • Flexibility – It is the ease of making changes.
          • Testability – It is the ease of testing the software.
      • Product Transition

These factors relate to adapting software to new environments and include-

• • • • • • Portability – It is the ease of transferring software to other systems.
          • Reusability – It is the ability to reuse components in other applications.
          • Interoperability – It is the ability to interact with other systems.
    • Advantages of McCall’s Quality Model
      • It clearly structured the software into three major categories.
      • It covers both operational and maintenance aspects.
      • It helps in systematic quality evaluation.
      • It is easy to understand for academic study.

• • • Boehm’s Quality Model is a software quality model proposed by Barry W. Boehm in 1978.
    • This model defines different quality characteristics to evaluate and measure the quality of a software product.
    • Boehm’s Quality Model is an important software quality framework that defines multiple (different) quality characteristics in a hierarchical form. It helps in evaluating and improving software performance, reliability, and maintainability.
    • This model focuses on improving software utility and maintainability.
    • Structure of Boehm’s Quality Model

Boehm’s model is divided into three levels:-

• • • • High-Level Characteristics
        • This level describes the overall utility of the software:-
          • As-is Utility – How well the software can be used in its current state.
          • Maintainability – Ease of modifying and updating the software.
          • Portability – Ease of transferring software to different environments.
      • Intermediate-Level Characteristics
        • These include:-
          • Reliability
          • Efficiency
          • Human Engineering (Usability)
          • Testability
          • Understandability
          • Maintainability
          • Portability
          • Flexibility
      • Primitive Characteristics
        • These are measurable attributes like:-
          • Completeness
          • Consistency
          • Accuracy
          • Structuredness
    • Advantages of Boehm’s Quality Model
      • It provides a hierarchical structure.
      • It covers both user and developer perspectives.
      • It helps improve maintainability and portability.
      • It is easy to understand and apply.

• • • The ISO 9126 Quality Model is a widely accepted international standard that defines six major characteristics to evaluate software quality. It helps organizations develop reliable, efficient, and user-friendly software systems.
    • It was developed by the International Organization for Standardization (ISO) to define a structured way to measure and assess software quality.
    • This model identifies the main characteristics that determine the quality of a software product.
    • The ISO 9126 model defines six primary quality characteristics:
      • Functionality
      • Reliability
      • Usability
      • Efficiency
      • Maintainability
      • Portability
    • Importance of the ISO 9126 model
      • It provides a standardized quality framework
      • It helps measure and evaluate software quality
      • It improves product reliability and performance
      • It ensures customer satisfaction