Software Quality and Reliability
Software quality is the degree to which software meets requirements and user expectations. Quality assurance focuses on processes; quality control focuses on products.
Quality Attributes
Key quality attributes include correctness, reliability (probability of failure-free operation), efficiency, usability, maintainability, portability, and security. ISO 25010 defines a comprehensive quality model.
Quality Assurance
SQA (Software Quality Assurance) is a set of activities ensuring quality throughout the process. It includes standards compliance, reviews and audits, testing, process improvement, and training. SQA is proactive — preventing defects rather than finding them.
CMM and CMMI
The Capability Maturity Model (CMM) defines five maturity levels: Initial, Repeatable, Defined, Managed, and Optimising. CMMI (CMM Integration) extends this framework. Higher maturity levels indicate more disciplined, predictable processes.
ISO Standards
ISO 9001 specifies quality management system requirements. ISO/IEC 12207 defines software lifecycle processes. ISO/IEC 25010 defines product quality model. Certification demonstrates commitment to quality and enables international business.
Software Reliability
Reliability is the probability of failure-free operation in a given environment for a given time. MTTF (Mean Time To Failure) and MTBF (Mean Time Between Failures) measure reliability. Reliability models predict failure rates from testing data.
Risk Management
Risk management identifies, analyses, and mitigates project risks. Steps: risk identification, risk analysis (probability × impact), risk prioritisation, risk mitigation planning, and risk monitoring.
Summary
Software quality requires systematic assurance, adherence to standards, reliability engineering, and proactive risk management. Maturity models and ISO standards provide frameworks for continuous improvement.