SQA Introduction

Software is: Computer programs, procedures, and

possibly associated documentation and data relates to the operation of a computer system.

[IEEE_Std_610.12-1990]

What is Software

1. Client developer communication failures2. Intended variation from software

requirements3. Coding errors4. Noncompliance with documentation and

coding instructions5. Shortcomings of the testing process6. User interface 7. Documentation errors fault

Some Causes of Software Errors

Conformance to requirements Lack of bugs High reliability (number of failures per n

hours of operation) Measured as Mean Time To Failure (MTTF)

What is Software Quality ?

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.

What is Software Quality ?

Software is a major component of computer systems◦ (about 80% of the cost) – used for communication

phone system, email 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

Importance of Software Quality

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

Importance of Software Quality

Internet viruses Exploit well known software vulnerabilities Usability problems

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Importance of Software Quality

The uniqueness of the software product High complexity Limited opportunities to detect defects

(“bugs”)

The Software Quality Challenge

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.