measuring signal to noise ratios using argument maps - request for pointers

I've become interested in the signal to noise ratios of different types of media and one way I've tried to measure it is simply count the number of posts it takes to represent a given item (e.g. a web forum or newspaper article) as an argument map, compared to the number of words in the item. I've done a few examples:

83 words/post for Wall Street Journal article on global warming
67 words/post for UK PIRC "climate safety" report
267 words/post for Italian Omniauto web forum
459 words/post for planeta carbon offsetting web forum
262 words/post for windmills web forum

The web forums, unsurprisingly, have substantially lower signal-to-noise ratios (i.e. more words per argument map entry) than the more polished articles and reports.

My question is: has anyone else done some projects where they created a map that represents all and only the content in a given article, web forum, or other corpus, so we could calculate the signal-to-noise ratio for them as well? This will enable to quantify, in some sense, one benefit of using arguments maps as a social medium - the results have a higher signal-to-noise ratio.

If you have some examples that allow calculating signal-to-noise ratios, could you let me know? I'll post whatever results I get in the GSM web site.

Thanks,

Mark Klein