Information Technology Reference
In-Depth Information
5.4.3 Problems of Volatility
Requirements will change over time. During the time it takes to develop a system,
the users' needs may mature because of increased knowledge brought on by the
development activities, or they may shift to a new set of needs because of
unforeseen organizational or environmental pressures. If such changes are not
accommodated, the original requirements set will become incomplete and incon-
sistent with the new situation, potentially creating an unusable system because the
captured information has since become obsolete. One primary cause of require-
ments volatility is that ''user needs evolve over time''. The requirements engi-
neering process of elicit, specify, and validate should not be executed only once
during system development, but rather should be returned to so that the require-
ments can reflect the new knowledge gained during specification, validation, and
subsequent activities. A requirements engineering methodology should be iterative
in nature, ''so that solutions can be reworked in the light of increased knowledge''.
Due to political climate and other factors, the needs of a particular group may be
overemphasized in the elicitation of requirements. Later prioritization of the
elicitation communities' needs may correct this oversight and result in require-
ments changes. Both the traceability of requirements and their consistency may be
affected if these changes are frequent and not anticipated. Organizational com-
plexity is another common cause of requirements volatility. Organizational goals,
policies, structures, and work roles of intended end users all may change during the
course of a system's development, especially as the number of users affected by a
system's development increases. Due to the problems of understanding and scope
discussed earlier, user needs may not be clearly expressed initially in the
requirements, and the developer or requirements analyst may make some incorrect
assumptions based on this ambiguity. With an iterative process, those mistaken
assumptions can be detected faster and corrected sooner.
5.5 Validating the Requirements
Validating requirements is the process of showing that the requirements define the
system in a fashion that accurately represents what the customer wants.
Requirement validation often results in reworking the elicitation process because
of errors discovered during development of the system. Recent techniques used for
validation are:
• Prototyping
• Quality Function Deployment
• Requirements Reviews
• Test case generation
