We began by collecting design principles and guidelines from the literature [4,3,8,12,13,16,17]. To limit the scope of the experiment we decided to use a subset of these principles, specifically Brown's collection of about 250 guidelines [5]. This collection was chosen because of its size and completeness. Each principle from this collection was placed on an index card. These cards were then grouped and regrouped, in an effort to co-locate principles that seemed related. If a principle seemed related to two groups, an evaluation of the groups was made, with one of three possible outcomes: