Possible correlation between citation and cost of content

Citation studies as of late indicate that freely available content, such as open access journals on the Web, is heavily cited. Others have observed that free content online can drive sales of physical facsimiles. (Consider this article about the National Academy Press published in 1999.) The studies conclude that, since such information is simply more findable and accessible than costly print or electronic journals online available in library databases, it is easier to cite.

Such a pattern appears to hold for another form of information: New York Times opinion columnists. The New York Times, in an effort to collect some revenue from the traffic to their Web site, decided recently to charge for "premium" content, including their columnists. I was disappointed, because now I have to read Maureen Dowd through Lexis-Nexis.

New York Times columnists are commonly cited by bloggers. But as this graph on the Daily Kos Web site indicates, these columnists are now being cited less after the New York Times started charging.

This is not surprising. Can a blogger realistically expect his or her audience to pay to read a column to which the blogger is responding? True, I cite the Chronicle of Higher Education all the time, but many of this blog's readers (I think) are librarians and students who have access through their respective institutions.

Note: The Daily Kos's source, BlogPulse, is admittedly opaque. Apparently BlogPulse is a blog search engine with tools that presumably can count the number of keywords occurring in blogs over a certain period of time.