Privacy and proportionality

Over the past several years, the press, trade publications and academic literature have reported with increasing frequency on the social concerns caused by ubiquitous computing---Information Technology (IT) embedded in artifacts, infrastructure and environments of daily life. Designers and researchers of ubiquitous computing (ubicomp) technologies have spent considerable efforts to address these concerns, which include privacy and data protection issues, information security and personal safety. Yet, designing successful ubicomp applications is still an unreliable and expensive endeavor, in part due to imperfect understanding of how technology is appropriated, the lack of effective design tools and the challenges of prototyping these applications in realistic conditions. I introduce the concept of proportionality as a principle able to guide design of ubiquitous computing applications and specifically to attack privacy and security issues. Inspired by the principle, I propose a design process framework that assists the practitioner in making reasoned and documented design choices throughout the development process. I validate the design process framework through a quantitative design experiment vis-à-vis other design methods. Furthermore, I present several case studies and evaluations to demonstrate the design method's effectiveness and generality. I claim that the design method helps to identify some of the obstacles to the acceptance of ubiquitous computing applications and to translate security and privacy concerns into research questions in the design process. I further discuss some of the inquiry and validation techniques that are appropriate to answer these questions.