SOFTWARE QUALITY CONCEPTS - Software Design for Six-Sigma: A Roadmap for Excellence - page 4

2001). One level for attaining quality is through inspection, which can be done
through a team-oriented process or applied to all stages of the software process
development. A second level for attaining quality is through formal methods, which
can be done through mathematical techniques to prove that the software does what
it is meant to do or by applying those mathematical techniques selectively. A third
level for attaining quality is through testing, which can be done at the component
level or at the application level. A fourth level is through project control techniques,
which can be done through predicting the cost and schedule of the project or by
controlling the artifacts of the project (scope, versions, etc.). Finally, the fifth level
we are proposing here is designing for quality at the Six Sigma level, a preventive
and proactive methodology, hence, this topic.
A quality function should have the following properties (Braude, 2001):
Satisfies clearly stated functional requirements
Checks its inputs; reacts in predictable ways to illegal inputs
Has been inspected exhaustively in several independent ways
Is thoroughly documented
Has a confidently known defect rate, if any
The American Society for Quality (ASQ) defines quality as follows: “A subjective
term for which each person has his or her own definition.” Several concepts are
associated with quality and are defined as follows 3 :
Quality Assurance : Quality assurance (QA) is defined as a set of activities whose
purpose is to demonstrate that an entity meets all quality requirements usually
after the fact (i.e., mass production). We will use QA in the Verify & Validate
phase of the Design For Six Sigma (DFSS) process in the subsequent chapters.
QA activities are carried out to inspire the confidence of both customers and
managers that all quality requirements are being met.
Quality Audits : Quality audits examine the elements of a quality management
system to evaluate how well these elements comply with quality system require-
ments.
Quality Control : Quality control is defined as a set of activities or techniques
whose purpose is to ensure that all quality requirements are being met. To achieve
this purpose, processes are monitored and performance problems are solved.
Quality Improvement : Quality improvement refers to anything that enhances an
organization's ability to meet quality requirements.
Quality Management : Quality management includes all the activities that man-
agers carry out in an effort to implement their quality policy. These activities
3 See ISO 13485, 2003.