As mentioned previously, usability testing is only one of the several techniques that can be used in user-centered design. These techniques are used at different stages of the product’s design and include focus groups, surveys, cognitive walkthroughs, heuristic evaluations, usability testing, field (ethnographic) studies and follow-up studies. Focus groups are helpful in evaluating the preliminary concepts surrounding the product with representative users. These issues can be explored in depth with relatively small groups and provide critical information on what the users want to be able to do with the product. Surveys are used to extrapolate product preferences or uses from a large group of individuals. These can be used to obtain user characteristics during the early phases of product design. Cognitive walkthroughs are used to explore how an end user might fare with a product by envisioning the user’s route through a paper prototype. This is usually performed with a designer present that guides and provides assitance to the user. Using these techniques on paper prototypes during early phases can be extremely resourceful as they are inexpensive and quick to set up, and provide some of the more critical information. Heuristic evaluations usually follow cognitive walkthroughs, and are performed using usability specialists or human factors professionals. These experts, using a set of ten usability principles, assess the usability of the product prototype by finding problems or concerns as they fit into each of the ten usability principles. These usability experts are not usually domain experts, for which the product is being designed. If a usability expert is also a domain expert, then he/she is refered to as a double specialist. These methodologies reveal some of the major design flaws that restrict usability, and these flaws have been resolved by the design team before the usability test. Once focus groups, market surveys, cognitive walkthroughs and heuristic evaluations have taken place, and the corresponding problems or issues have been resolved then a usability test is performed on the product. Once all of the major problems and user concerns have been taken care of after repeated usability tests, and the product has entered the market place, then field (ethnographic) studies provide information on how the product is used and performs in real work (world) settings. This information may not result in drastic changes in the product’s design, but can provide suggestions on future releases of the product. Follow-up studies collect user information in a more structured way, in an attempt to better understand the need of another related product.