Researchers and developers generally agree that user interface problems are more easily solved at the beginning of the design process than toward the end. It is much less costly to make changes to the user interface before significant effort has been put into the development of software. One way to evaluate a user interface is to ask representative users to perform specific tasks using a prototype and provide feedback on the system's ease of use. A prototype can mimic a system's functionality without containing any knowledge of the specific application.
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