title: An exploratory analysis of PubMed's free full-text limit on citation retrieval for clinical questions.
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.
authors.affiliation: Information Services, Medical Center Library, Saint Louis University, 1402 South Grand Boulevard, St. Louis, MO 63104, USA. kriegerm@slu.edu
authors.forename: Mary M
authors.initials: MM
authors.lastname: Krieger
authors.forename: Randy R
authors.initials: RR
authors.lastname: Richter
authors.forename: Tricia M
authors.initials: TM
authors.lastname: Austin
mesh_terms: D000043:Abstracting and Indexing / Q000706:statistics & numerical data*; D015706:Bibliometrics; D006801:Humans; D016247:Information Storage and Retrieval / Q000706:statistics & numerical data*; D046650:Medical Subject Headings / Q000706:statistics & numerical data*; D010506:Periodicals as Topic / Q000706:statistics & numerical data; D039781:PubMed / Q000706:statistics & numerical data*; D011643:Publishing; D014481:United States; D018875:Vocabulary, Controlled