“…A research stream related to collaborative tagging is concerned about viewing social tags as indexing terms, including the analysis of tags in syntactic structure, linguistic function, etc (Kipp & Campbell, 2006;Spiteri, 2007), the examination of tags across different tagging systems (Heckner, Muhlbacher, & Wolff, 2007), and the attempt to link tags to controlled vocabularies such as Library of Congress Subject Headings (Yi & Chan, 2009). Some theoretic models were attempts to describe social tagging activities: basic Polya Urn model (Golder & Huberman, 2006) for tag generation, YuleSimon model (Cattuto, Baldassarri, Servedio, & Loreto, 2007) for the growth of tags, and power law (Dellschaft & Staab, 2008) for tag frequency-rank distribution. Nevertheless, there are only a few studies, including (Yi, 2009a), that attempt to directly quantify and measure the value of social tags as indexing terms.…”