After figuring out that not everyone would use the Pub2Conn/Pub2CiteULike tool, I checked the bookmarkings in both sites.  Some of the Connotea citations listed the PMID; some did not.  Some of the remaining Connotea citations did connect directly to PubMed; some did not.  Same for CiteULike.

I have reviewed tags in both sites; the work is going slowly because I am doing it manually.  The number of Connotea tags that equal the citations’ PubMed MeSH terms = 17/71 (23.943662%).  The number of tags with both Connotea/PubMed connection = 39/71 (54.9295775%).  The number of CiteULike tags that equal the citations’ PubMed MeSH terms = 21/80 (26.25%).  The number of tags with both CiteULike/PubMed connections = 56/80 (70%).

Can’t wait to get more information; is this a pattern?