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ISBN: 978-972-8939-25-0 © 2010 IADIS4.1 Measuring Tag QuantitySince the success of the whole concept depends on automatically applying tags to the resources of a Webbased encyclopedia system we first conducted an experiment measuring tag quantity, i.e. we measured: Thenumber of tagged resources (#r) over time, the number of newly tagged resources over time (#r new ), thenumber of generated tags (#t) over time and the number of newly generated tags over time (#t new ).Essentially, we could observe that QueryCloud annotates in general nearly 150 resources every day whichis actually 3 times as many resources as the human taggers do annotate within Austria-Forum in the sameperiod of time. Regarding the number of generated tags, we could observe that QueryCloud produces inaverage nearly 4 times as many tags as the human taggers do (see Figure 4) which is at least 266 generatedtags a day.Figure 4. Number of tagged resources and number of generated tags over time for Austria-Forum: QC dataset (blue lines)vs. AF dataset (red lines).4.2 Measuring Link QualityAfter measuring the quantity of the tags produced by QueryCloud system we had a closer look at the actual“link quality” of the produced tags by QueryCloud system. Since the success of the whole concepts isdepended on linking related documents over tags that share more than one resource with each other, weconducted an experiment measuring the number orphan tags produced by QueryCloud system. Orphan tags(cf. Körner et al. 2010) are basically tags which are applied to only one resource within a tagging system, i.e.they do not connect any resources with each other. Again, we could observe that QueryCloud systemperforms really well by actually producing 7% less orphan tags than the human taggers (AF) do withinAustria-Forum (see Table 1).Table1. Number of tags (#tags) and number of orphan tags (#orphans): QC dataset vs. AF dataset#tags#orphansQC dataset 49,416 34,962 (70%)AF dataset 11,479 8,845 (77%)4.3 Measuring Network QualityAnother metric we were interested in was the so-called “network quality” of QueryCloud system. In order tomeasure this property we first modeled QueryCloud resource-specific tag cloud network as a simple tagresourcebipartite graph system of the form V = R∪T, where R is the resource set and T is the query tag set(Helic et al. 2010). Since the “link quality” experiment only showed us how many actual useful tags thesystems generates (by means of connecting two or more resources) we conducted an additional experiment to238