title: Search filter precision can be improved by NOTing out irrelevant content.
abstract: BACKGROUND
  Most methodologic search filters developed for use in large electronic databases such as MEDLINE have low precision. One method that has been proposed but not tested for improving precision is NOTing out irrelevant content.
  
  
  OBJECTIVE
  To determine if search filter precision can be improved by NOTing out the text words and index terms assigned to those articles that are retrieved but are off-target.
  
  
  METHODS
  Analytic survey.
  
  
  METHODS
  NOTing out unique terms in off-target articles and testing search filter performance in the Clinical Hedges Database.
  
  
  METHODS
  Sensitivity, specificity, precision and number needed to read (NNR).
  
  
  RESULTS
  For all purpose categories (diagnosis, prognosis and etiology) except treatment and for all databases (MEDLINE, EMBASE, CINAHL and PsycINFO), constructing search filters that NOTed out irrelevant content resulted in substantive improvements in NNR (over four-fold for some purpose categories and databases).
  
  
  CONCLUSIONS
  Search filter precision can be improved by NOTing out irrelevant content.
authors.affiliation: Health Information Research Unit, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Wilczynski
authors.forename: K Ann
authors.initials: KA
authors.lastname: McKibbon
authors.forename: R Brian
authors.initials: RB
authors.lastname: Haynes
mesh_terms: D016206:Databases, Bibliographic; D016247:Information Storage and Retrieval / Q000379:methods*; D016239:MEDLINE; D012680:Sensitivity and Specificity