Designing devices and user interfaces closely relates to the evaluation of the same. In fact, the evolution that takes place from the first prototype and idea to the final and commercialized product includes a number of iterations, which should always occur as a result of evaluations. These evaluations, that should be as systematic as possible, can be done by experts, with final users, or, in ideal conditions, with both. During these evaluation phases an internal tool named Fraunhofer Usage Mining (FUSAMI) is used, to record the user interaction and to analyse the gathered data using advanced statistical methods and visualize the results. Nothing justifies an untested product and we should always make sure that nothing reaches the market without being tested and iteratively redesigned first. At Fraunhofer AICOS, our researchers keep a close contact with the end-users, who we consult and with whom we work on a regular basis. This is possible through a number of partnerships with end-user institutions.