Software is:  Computer programs, procedures, and possibly associated documentation and data relates to the operation of a computer system. [IEEE_Std_ ]

1. Client developer communication failures 2. Intended variation from software requirements 3. Coding errors 4. Noncompliance with documentation and coding instructions 5. Shortcomings of the testing process 6. User interface 7. Documentation errors fault

 Conformance to requirements  Lack of bugs  High reliability (number of failures per n hours of operation)  Measured as Mean Time To Failure (MTTF)

 According to the IEEE  Software quality is: (1) The degree to which a system, component, or process meets specified requirements.  (2) The degree to which a system, component, or process meets customer or user needs or expectations.

 Software is a major component of computer systems ◦ (about 80% of the cost) – used for communication phone system, system) ◦ Health monitoring, ◦ Transportation (e.g. automobile, aeronautics), ◦ Economic exchanges (e.g. ecommerce)  Software defects are extremely costly in term of ◦ money ◦ reputation ◦ loss of life

 1988 shooting down of Airbus 320 by the USS Vincennes cryptic and misleading output displayed by tracking software  1991 patriot missile failure inaccurate Calculation of time due to computer arithmetic errors  ETC

 Internet viruses  Exploit well known software vulnerabilities  Usability problems Small text that can’t be resized Pop-up presentation

 The uniqueness of the software product  High complexity  Limited opportunities to detect defects (“bugs”)

Quality Concepts Software quality assurance is an umbrella activity that is applied throughout the software process. Quality --> refers to measurable characteristics of a software. These items can be compared based on a given standard Two types of quality control: - Quality design -> the characteristics that designers specify for an item. --> includes: requirements, specifications, and the design of the system. - Quality of conformance -> the degree to which the design specification are followed. It focuses on implementation based on the design.