Open Access News

News from the open access movement


Friday, October 31, 2008

Costs of limiting PubMed searches to Free Full Text

Mary M. Krieger, Randy R. Richter, and Tricia M. Austin, An exploratory analysis of PubMed's free full-text limit on citation retrieval for clinical questions, Journal of the Medical Library Association, October 2008.  Abstract:  

Objective:  The research sought to determine (1) how use of the PubMed free full-text (FFT) limit affects citation retrieval and (2) how use of the FFT limit impacts the types of articles and levels of evidence retrieved.

Methods:  Four clinical questions based on a research agenda for physical therapy were searched in PubMed both with and without the use of the FFT limit. Retrieved citations were examined for relevancy to each question. Abstracts of relevant citations were reviewed to determine the types of articles and levels of evidence. Descriptive analysis was used to compare the total number of citations, number of relevant citations, types of articles, and levels of evidence both with and without the use of the FFT limit.

Results:  Across all 4 questions, the FFT limit reduced the number of citations to 11.1% of the total number of citations retrieved without the FFT limit. Additionally, high-quality evidence such as systematic reviews and randomized controlled trials were missed when the FFT limit was used.

Conclusions:  Health sciences librarians play a key role in educating users about the potential impact the FFT limit has on the number of citations, types of articles, and levels of evidence retrieved.

Comment.  In short, work for OA but don't assume that all valuable literature is already OA.