title: Preparation of name and address data for record linkage using hidden Markov models.
abstract: BACKGROUND
  Record linkage refers to the process of joining records that relate to the same entity or event in one or more data collections. In the absence of a shared, unique key, record linkage involves the comparison of ensembles of partially-identifying, non-unique data items between pairs of records. Data items with variable formats, such as names and addresses, need to be transformed and normalised in order to validly carry out these comparisons. Traditionally, deterministic rule-based data processing systems have been used to carry out this pre-processing, which is commonly referred to as "standardisation". This paper describes an alternative approach to standardisation, using a combination of lexicon-based tokenisation and probabilistic hidden Markov models (HMMs).
  
  
  METHODS
  HMMs were trained to standardise typical Australian name and address data drawn from a range of health data collections. The accuracy of the results was compared to that produced by rule-based systems.
  
  
  RESULTS
  Training of HMMs was found to be quick and did not require any specialised skills. For addresses, HMMs produced equal or better standardisation accuracy than a widely-used rule-based system. However, accuracy was worse when used with simpler name data. Possible reasons for this poorer performance are discussed.
  
  
  CONCLUSIONS
  Lexicon-based tokenisation and HMMs provide a viable and effort-effective alternative to rule-based systems for pre-processing more complex variably formatted data such as addresses. Further work is required to improve the performance of this approach with simpler data such as names. Software which implements the methods described in this paper is freely available under an open source license for other researchers to use and improve.
authors.affiliation: Centre for Epidemiology and Research, Public Health Division, New South Wales Department of Health, Locked Mail Bag 961, North Sydney 2059, Australia. tchur@doh.health.nsw.gov.au
authors.forename: Tim
authors.initials: T
authors.lastname: Churches
authors.forename: Peter
authors.initials: P
authors.lastname: Christen
authors.forename: Kim
authors.initials: K
authors.lastname: Lim
authors.forename: Justin Xi
authors.initials: JX
authors.lastname: Zhu
mesh_terms: D003625:Data Collection / Q000379:methods* / Q000706:statistics & numerical data; D003661:Decision Support Techniques; D008390:Markov Chains; D008490:Medical Informatics / Q000639:trends; D008498:Medical Record Linkage / Q000379:methods*; D012984:Software / Q000706:statistics & numerical data; D012986:Software Validation