A storyboard can be used in two ways, firstly during the design of a user interface as a way of expressing and understanding the way users will eventually interact with the system. Secondly they can be used during early evaluation of a user interface design to get user feedback before a prototype is constructed.

Prototype and evaluate

Prototyping

Prototyping is a way of showing the idea behind a design in an inexpensive way. The prototype can be changed easily and the design evolved gradually to an optimal solution before the system is implemented. The idea behind prototyping is to save on the time and cost to develop something that can be tested with real users. A prototype can come in a variety of forms. These may be a paper-based mock-up, using paper card, and postits to demonstrate screens and different interface elements. They are normally developed in software using a visual design system such as Visual Basic. However for Multimedia design tools such as Macromedia Director or Asymmetrix Toolbook are good tools for mocking up screens. A prototype need not show all parts of the system and need not have a full database, but should have enough content to show the ideas behind the design. As the prototype become accepted more details can be added allowing the refine the design.

Evaluation

Prototypes form the basis for evaluation of the system design. This evaluation may either be expert based where one or more task or human factors experts review the system and diagnose different problems to address or alternatively good features to build on. However it is important that some form of user-based evaluation is carried out either informally or formally. Informal evaluations involve the evaluator working individually with a group of users looking either at the different parts of the prototype in a structured way, or by using the system to try and perform specific tasks in a step-by-step fashion. The user comments on the system while the evaluator makes notes which he or she will normally compile into a report. In a formal evaluation, the user will be given a series of tasks to perform and see how well they can achieve them. The evaluation may record the useršs performance and their opinions by answering a series of questions of expressing their attitude using a set of rating scales. Here the evaluator will normally stand back to observe how well the user can perform the tasks while only providing help if the user gets stuck. This type of test is the most stringent and is recommended at some stage in the design of any interactive system.