Dumas & Redish lay-out the steps and tactics for recruiting participants; those include: Finding Appropriate Participants, Reaching and Screening Potential Participants, Deciding Who Should Recruit Participants, Knowing What to Say When You are Recruiting, Arranging for Payment or Other Incentives, and Having a Back-up -- But Not Double Booking
Entropy can be characterized by the term ‘randomness’ to express the phase duration in which a stable system’s state mutates due to expected or unexpected variables.
According the Mark Weiser and John Seely Brown (1996), "peripheral information" extends the notion of "affordances" to describe action enabling technologies that are reachable, yet on the periphery of perception and therefore encalming.
Testing has two main objectives: on the marketing level, it aims at improving sales; on a user-centered level, it aims at minimizing user frustrations and maximizing a product's usability. As the authors point out, testing goals inform the design of a product; those work in terms of the usefulness or relevance, learnability, efficiency, effectiveness, and satisfaction factors.
Bill Buxton defines "best practices" in designing for user experiences as a combination of both methods and skills relating to ideation: sketching, testing and problem-solving.
