requirements: how to specify, test and report usability
Why does usability matter?
Customers have increasing expectations of usability, so when developing
a product it is important to include usability with other requirements
and ensure that the usability requirements have been met.
Incorporating user-centred methods into the development process
can reduce development time, increase sales and reduce support costs.
Reduced development time
Focussing on user and organisational needs will reduce the development
- reducing the late changes otherwise needed to produce a product
that meets user needs
- reducing the cost of future redesign of the architecture to
make future versions of the product more usable
- marketing the product as easier to use than the competition
provides an increased competitive edge
- repeat sales will be made to more satisfied customers
- the usability of the product will be given higher ratings in
the trade press
- reduced costs of producing training materials
- reduced help line support
See the case studies for
examples of the benefits that can be obtained by suppliers.
Usability as part of a contract with the customer
The customer may wish to include usability requirements in the
contract. Issues to consider when negotiating the content of the
- To be meaningful the requirements should specify task scenarios
which are realistic for the customers users.
- It is difficult to assess the cost and risk of developing a
system to meet specific performance and satisfaction criteria,
unless these are derived from an existing comparable system (see
UsabilityNet for more
details). Requirements that the new system must be at least
as usable as the existing system provide reasonable assurance
for the customer without being unduly demanding for the supplier.
© 2002 Serco Ltd. Reproduction permitted provided the source is acknowledged.