Design Considerations
Requirements Gathering
Envisionment Methods
Evaluation
Other
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Requirements gathering and Analysis
- A requirement is something the product must do or a quality that the
product must have
- Users may not be aware of all requirements
- Users may voice a perceived need
- But users do not mention some requirements
- assume that the requirement is obvious
- good interviews, observation
will help to reveal these
- some only surface when models are constructed or prototypes
are reviewed
- users also may not appreciate technical possibilities (or impossibilities)
- early prototyping helps here
2 types of requirements
- Functional requirements
- Non-functional requirements
Functional requirements
What the system must do
- specifications of the system’s functionality
- actions that the system must take (verbs)
- not a quality e.g. ‘fast’
- take care to be precise & unambiguous
Non-functional requirements
A quality that the system must have (adjectives or adverbs)
- secure, reliable, quickly, easy to use, compliant with Data Protection
legislation
- often about image in consumer products
- customer and user may judge product mainly on nonfunctional qualities
- again must be precise and unambiguous
Different types of nonfunctional requirements
- look and feel
- spirit of the product’s appearance, aesthetics, trendy or
corporate
- do what users expect
- not detailed design
- usability
- specify ease to use by whom, with what
skills or training
- also ease of learning
- user acceptance
- productivity gains
- error rates
- use by non-(English) speakers
- accessibility
- performance
- speed
- safety
- throughput
- accuracy
- reliability
- availability
- operational
- technical environment
- physical environment
- security
- confidentiality
- recovery after emergencies
- safe storage
Examples
Requirements for PDA hospital system
It is impossible to design a (usable?) system without knowledge of
- who will use it?
- where will they use it?
- what will they use it for?
- how will they use it?
- what will reduce their effectiveness in using the system?
- what will reduce your effectiveness in designing the system?
- what are the agendas of the people involved, hidden or otherwise?
Some methods used to ascertain the answers to the above questions include
- ethnography
- Interviews *
- Focus Groups *
- User Logging
- Questionnaires
- technology tour
- task analysis *
- end user profiling *
- pact analysis *
- cultural probes
- artefact collection
- activity theory
Methods marked with * are the ones we will concentrate on for this module.
Others are available for your information.