The contributions of this thesis are situated in the field of Human-Computer Interactions (HCIs), a field "concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them" [Hewett et al., 2014]. Each of the main contributions presented in this thesis is substantiated in one or more observational studies or controlled experiments. All of the studies and experiments were designed, conducted, and analyzed according to widely accepted standards of the HCI community [Lazar, J. H. Feng, and Hochheiser, 2010]. This section describes the general approach to the design and analysis, which applies to all studies presented. Any exceptions are mentioned and justified in the respective chapters.
Study DesignIn this thesis, two general types of study designs are applied, controlled experiments and observational studies.