Understanding How Users Edit Ontologies: Comparing Hypotheses About Four Real-World Projects.

Ontologies are complex intellectual artifacts and creating them requires significant expertise and effort. While existing ontology-editing tools and methodologies propose ways of building ontologies in a normative way, empirical investigations of how experts actually construct ontologies \"in the wild\" are rare. Yet, understanding actual user behavior can play an important role in the design of effective tool support. Although previous empirical investigations have produced a series of interesting insights, they were exploratory in nature and aimed at gauging the problem space only. In this work, we aim to advance the state of knowledge in this domain by systematically defining and comparing a set of hypotheses about how users edit ontologies. Towards that end, we study the user editing trails of four real-world ontology-engineering projects. Using a coherent research framework, called HypTrails, we derive formal definitions of hypotheses from the literature, and systematically compare them with each other. Our findings suggest that the hierarchical structure of an ontology exercises the strongest influence on user editing behavior, followed by the entity similarity, and the semantic distance of classes in the ontology. Moreover, these findings are strikingly consistent across all ontology-engineering projects in our study, with only minor exceptions for one of the smaller datasets. We believe that our results are important for ontology tools builders and for project managers, who can potentially leverage this information to create user interfaces and processes that better support the observed editing patterns of users.