What is software quality? What are McCall and ISO 9126 Quality factors?

To achieve a software of high quality is an ultimate goal. Software quality is assessed by internal and external quality criteria. External quality is critical to the user, while internal quality is meaningful to the developer only. Software quality is a mix of factors that vary across different applications and customers who request them.

McCall's Quality Factors
Software quality is affected by the factors that can be measured directly or indirectly. These include:
- During product operation, factors include correctness, reliability, usability, integrity and efficiency.
- During product transition, factors include portability, re-usability and inter-operability.
- During product revision, factors include maintainability, flexibility and test-ability.

ISO 9126 Quality Factors
This ISO was developed to identify quality attributes which includes:
- Functionality which includes the extent to which software is available for use indicated by sub attributes like suitability, accuracy, inter-operability, compliance and security.
- Reliability is amount of time software is available for use indicated by sub attributes like maturity, fault tolerance and recover-ability.
- Usability is the degree to which software is easy to use indicated by sub attributes like understand-ability, learn-ability and oper-ability.
- Efficiency is the extent to which software makes optimal use of resources indicated by sub attributes like time and resource behavior.
- Maintainability is an ease with which repair can be made to the software indicated by sub attributes like changeability, stability, testability.
- Portability is the ease with it can be transported from one environment to another indicated by sub attributes like adaptability, replace-ability.

What are different activities that comprise Software Quality Assurance?

To build a quality software, software quality assurance comprise of different activities. People involved are development team and software quality assurance team. The team of software quality assurance is responsible for quality assurance planning, overseeing, analyzing, record keeping, defects analysis and rework.

The activities encompassing software quality assurance are:
- Software Quality Assurance Plan is prepared by SQA team. They identify the evaluation to be performed, audits and reviews to be performed, standards that are applicable, procedures for error reporting and tracking, documents to be produced and amount of feedback required.
- SQA team checks if the selected software development process conform to the organizational policy and quality standards.
- SQA team monitor and track deviations from the software development process. It reviews software engineering activities.
- SQA team reviews, monitor and track defects found with each work products. Documentations are done to ensure that corrections have been made.
- The SQA team ensures that deviations in the software activities and work products are handled based on defined standard operating procedures.
- The SQA team reports deviations and non-compliance to standards to the senior management or stakeholders.

Software quality assurance plans saves time, money, increases productivity, enhances training, provides extra support.

What is Software Quality Assurance (SQA)? What are characteristics of a well-engineered software?

Software Quality Assurance(SQA) is a function of software quality that assures that the standards, processes, and procedures are appropriate for the project and are correctly implemented.
- It is a subset of software engineering that ensures that all deliverables and work products are meet, and they comply with user requirements and standards.
- Its goal is to detect defects before the software isdelivered as a final product to the end-users.
- It includes quality management approach.
- It includes effective methods and tools.
- It includes formal technical reviews.
- It includes a multi-tiered testing strategy.
- It includes control of software documentation.
- It includes a procedure to assure compliance with software development standards, and measuring and reporting mechanism.

How do we say that the software is well-engineered?

- A software should be easy to use by the user.
- A software should have the capability to be able to execute on different platforms.
- A software should be able to transfer from one system to another.
- A software should be able to evolve and adapt to changes over time.
- A software should be reliable, secure and safe.
- A software should be capable of using resources efficiently.

A software has quality if it is fit for use, i.e., it is working properly. It should conform to explicitly stated user's external characteristics, explicitly documented quality standards and implicit characteristics.