title: The Zipper: a method for using personal identifiers to link data while preserving confidentiality.
abstract: OBJECTIVE
  This report describes a method for linking separate confidential data sets that contain personal identifying information while preserving required anonymity.
  
  
  METHODS
  Research data were linked with child abuse and neglect (CAN) report data by an independent "safe" analyst using an identical set of unique identifier codes assigned to each case in both data sets after all personal identifiers had been removed.
  
  
  RESULTS
  The research team never learned CAN report status of individuals, the state agency never saw the research data, and the desired analyses were completed using the merged data set.
  
  
  CONCLUSIONS
  The method was successfully used to merge data from separate sources without divulging confidential information.
authors.affiliation: Center for Family Medicine Science in the Department of Family and Community Medicine, School of Medicine, University of Missouri-Columbia, 65212, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Kruse
authors.forename: B G
authors.initials: BG
authors.lastname: Ewigman
authors.forename: G C
authors.initials: GC
authors.lastname: Tremblay
mesh_terms: D000043:Abstracting and Indexing; D002648:Child; D002649:Child Abuse / Q000706:statistics & numerical data*; D016494:Computer Security; D003219:Confidentiality; D003625:Data Collection; D016208:Databases, Factual; D006801:Humans; D008498:Medical Record Linkage; D008923:Missouri; D010355:Patient Identification Systems; D012107:Research Design / Q000592:standards*