Measuring and Ensuring Similarity of User Interfaces: The Impact of Web Layout

Given the rapid update cycles in modern web information systems and the abundance of legacy software being migrated to the web, controlling similarity between user interfaces (UI) is an actual problem of interaction engineering. The similarity (consistency) aspect is also increasingly considered in computer-aided design, where it is included in the optimized goal function, to minimize re-learning effort for users. In this paper, we explore the impact of the proposed layout distance measure, which is calculated for different levels of hierarchy in web UIs, which we identify as: Region - Block - Group - Element. To support our approach, we conducted an experimental pilot study in the context of an ongoing medical information system (IS) web migration project. The regression analysis suggests that layout distance (particularly, its orientation dimension) does have effect on web UI similarity as perceived by users. The results can be used by web engineers, in particular to smoothen the transition between versions of a UI for users and IS operators.