Table 4.

Details of the user study and the compared data sets The table displays statistics about the user study and the ontologies. The most similar values to the user study are displayed in bold face. For the first three measures, we viewed the information about found targets, visited Wikipedia Pages and first hops as a vector of values, for which we calculated the angle to the vector containing the information for the user study (i.e., the cosine similarity). For the random walk, we averaged over 1000 random walks for each portal-target pair. The last two measures display the average per step usage of the back and home buttons for the different scenarios. In summary, the results confirm that what has appeared somewhat apparent from the success ratios and the stretch, i.e., that ICD-10 and MeSH displayed the most similar behavior to the user study. The randomly generated ontology column was computed using an average over the three randomly generated ontologies considered.

		User Study	ICD-10	MeSH	SNOMED-CT	Optimal	Random Ontology	Random Walk
Found targets (Cosine Similiarity)	Single	1.00	0.93	0.95	0.89	0.95	0.78	0.72
	Multiple	1.00	0.94	0.94	0.91	0.95	0.90	0.67
First Hops (Cosine Similiarity)	Single	1.00	0.89	0.85	0.69	0.88	0.77	0.80
	Multiple	1.00	0.64	0.62	0.56	0.68	0.64	0.71
Back Button Uses (average per step)	Single	0.09	0.13	0.11	0.13	0.00	0.26	0.07
	Multiple	0.27	0.17	0.18	0.18	0.01	0.21	0.09
Home Button Uses (average per step)	Single	0.02	0.00	0.00	0.00	0.00	0.01	0.00
	Multiple	0.01	0.03	0.02	0.03	0.00	0.05	0.00