Philip M. Davis has written a “review of the empirical literature on access to scholarly information. This review focuses on surveys of authors, article download and citation analysis.”  The pre-print is available in Arxiv: http://arxiv.org/abs/0912.3953v1

Excerpts:

In reviewing the literature, there is surprising consistency in the conclusions of these studies: access to the published literature is improving, and those who generate knowledge view access issues as largely unimportant. We should emphasize the phrase “those who generate knowledge,” since there has been very little work on the dissemination of scientific information to those who use – but do not contribute to – the literature (i.e. teachers, medical practitioners, industrial researchers, and the lay public).

Moreover, most studies have focused on access to the formal, published literature and assume that access is provided either directly from the publisher or through a library intermediary. We should not ignore the many informal ways academics share documents among informal networks of peers. Lastly, we should understand that most of the surveys and interviews cited below were conducted prior to the recent economic downturn, which have resulted in significant material reductions in major academic libraries.

from the Conclusion:

In conclusion, the literature on the access indicates that access to the scientific literature is improving, and that compared to other research-related concerns, access is a low-priority concern. There is a dearth of research on whether free access to the scientific literature is making a difference in non-research contexts, such as in teaching, medical practice, industry and government policy making. Moreover, more work needs to be done on the dissemination of scientific papers through non-formal models such as peer-to-peer sharing networks.

Sen. Charles Grassley, an Iowa Republican who is a leading critic of conflicts of interest in biomedical research, is focusing on the issue of journal ghostwriting. The New York Times reported that he has written to 10 medical schools, asking about whether they have policies that deal with issues raised by pharmaceutical companies ghostwriting articles that appear under the names of university researchers.

NYT excerpt:

Mr. Grassley, of Iowa, the ranking Republican on the Senate Finance Committee, sent the letters as part of his continuing investigation of so-called medical ghostwriting. The term refers to publication of medical journal articles in which an outside writer — sometimes paid by a drug or medical devices company whose product is being studied — has done extensive work on the article without being named on the publication. Instead, one or more academic researchers may receive author credit.

Mr. Grassley said ghostwriting had hurt patients and raised costs for taxpayers because it used prestigious academic names to promote medical products and treatments that might be expensive or less effective than viable alternatives.