Usability requirements: how to specify, test and report usability

Guide for suppliers

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 time by:

  • 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

Increased sales

  • 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

Support savings

  • 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 contract include:

  • To be meaningful the requirements should specify task scenarios which are realistic for the customer’s 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.

Copyright © 2002 Serco Ltd. Reproduction permitted provided the source is acknowledged.