Quality Requirement
- Quality Requirement
- any requirement
that specifies a minimum required amount (threshold) on a quality measure of a
quality criteria
characterizing a
quality factor or
quality subfactor
As illustrated in the preceding figure, Quality Requirement is part of the following inheritance hierarchy:
The typical responsibilities of a quality requirement are to:
- Specify the manner in which something must perform its
functions.
- Ensure that the application or component has the
necessary quality factors or quality subfactors needed by
the:
- Development organization during development.
- Maintenance organization during maintenance.
- User organization(s) during usage.
- Specify a required observable quality attribute or characteristic.
The following guidelines have been found to be useful when producing quality requirements:
- A quality requirement should be specified in terms of the components of a standardized quality model:
- Although quality requirements are often termed “non-funtional” requirements to differentiate
them from the functional requirements, this is actually a
misnomer because the non-functional requirements include data
requirements, external API requirements, and constraints as well as the quality requirements.
- Quality requirements are often characterized by adjectives, whereas functional requirements are often
characterized by verbs.
- Quality requirements often have major impacts on architectures, effort, costs, and schedules.
- In practice, requirements teams typically concentrate on functional requirements
and therefore spend too little time on quality requirements.
- Whereas requirements engineers (and architects) often understandt the critical nature of quality requirements, they
often are not adquately trained in how to properly analyze and specify them.
- Many quality requirements are difficult to quantify and
are too often documented as goals rather than validatable requirements.
- Most quality requirements are really system-level requirements rather than software requirements because they
can only be achieved via the collaboration of data, hardware, software, and (potentially) personnel components.
- A quality requirement is typically specified in the quality requirements section of the
system requirements specification.
- A quality requirement may be specified indirectly in the
standard constraints section of the system requirements
specification if the standard specifies quality requirements.
