Gauging Ontologies and Schemas by Numbers

We survey nearly 1300 OWL ontologies and RDFS schemas. The collection of statistical data allows us to perform analy- sis and report some trends. Though most of the documents are syntactically OWL Full, very few stay in OWL Full when the syntactic errors are fixed. We also report the frequency of occurrences of OWL language constructs and the shape of class hierarchies in the ontologies. Finally, we note that of the largest ontologies surveyed here, most do not exceed the expressivity of ALC.