“Usability insights also help later in the project, and there is value in fine-tuning user interface details, but late-stage changes impact the final user experience less than fundamental changes early in the design. It’s a rough estimate, but I would say that the benefits from early usability data are at least ten times greater than those from late usability data….. The most common estimate is that it’s 100 times cheaper to make a change before any code has been written than it is to wait until after the implementation is complete.” Jakob Nielsen reviews Carolyn Snyder’s book
—Paper PrototypesAlert Box)
Nielsen doesn’t actually explain what a paper prototype is — a method of roughing out the way you want the computer to look by using sketches on paper, and flipping back and forth between them to simulate how the computer changes in response to user input. Beginning web designers may find this technique very helpful, since it lets them experience the flow of their documents, and make changes in that flow, before they invest time in creating their prototypes.