A.4 Ethnography
? A social scientists spends a considerable time observing and analysing how people actually
work
? People do not have to explain or articulate their work
? Social and organisational factors of importance may be observed
? Ethnographic studies have shown that work is usually richer and more complex than
suggested by simple system models
3.4.5 Requirements validation
A.1 Concerned with demonstrating that the requirements define the system that the
customer really wants
A.2 Requirements error costs are high so validation is very important
? Fixing a requirements error after delivery may cost up to 100 times the cost of fixing an
implementation error
3.4.6 Requirements change management
B.1
Requirements management is the process of managing changing requirements during the requirements engineering process and system development
B.2 Requirements are inevitably incomplete and inconsistent
? New requirements emerge during the process as business needs change and a better
understanding of the system is developed
? Different viewpoints have different requirements and these are often contradictory
3.5 Key points
1. Requirements for a software system set out what the system should do and define constraints
on its operation and implementation.
2. Functional requirements are statements of the services that the system must provide or are
descriptions of how some computations must be carried out.
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3. Non-functional requirements often constrain the system being developed and the
development process being used.
4. They often relate to the emer