How do the role and timing of user testing in user-centered development differ from more traditional software engineering methodologies?

What will be an ideal response?

In traditional methodologies, users play a role at two stages. After an initial consultation during the needs analysis stage, users are isolated from the process until the beta-test stage, which occurs just before product release. However, at this point, almost the entire development budget has been spent, and there is very little money left for making changes. Only the most critical problems of functionality get fixed.
In contrast, a user-centered approach performs user testing early and often. With this approach many usability problems can be caught and remedied before developers write any code or format any Web pages.