Understanding Relevance Score of OpenCalais

I am trying to understand what is the relevance score that opencalais returns associated with each entity? What does it signify and how is it to开发者_运维百科 be interpreted? I would be thankful for insights into this.

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Their documentation states: The relevance capability detects the importance of each unique entity and assigns a relevance score in the range 0-1 (1 being the most relevant and important).

While they do not explain what 'relevance' means exactly, one would expect it to quantify the centrality of the entity to the discourse of the document. It's likely influenced by factors such as the entities mention frequency in this document as compared to its expected frequency in a random document (cf. TF-IDF), but could also involve more sophisticated discourse analysis.