title: Sampling methodology and site selection in the National Eye Health Survey: an Australian population-based prevalence study.
abstract: BACKGROUND
  This paper presents the sampling methodology of the National Eye Health Survey that aimed to determine the prevalence of vision impairment and blindness in Australia.
  
  
  METHODS
  The National Eye Health Survey is a cross-sectional population-based survey.
  
  
  METHODS
  Indigenous Australians aged 40 years and older and non-Indigenous Australians aged 50 years and older residing in all levels of geographic remoteness in Australia.
  
  
  METHODS
  Using multistage, random-cluster sampling, 30 geographic areas were selected to provide samples of 3000 non-Indigenous Australians and 1400 Indigenous Australians. Sampling involved (i) selecting Statistical Area- Level 2 sites, stratified by remoteness; (ii) selecting Statistical Area- Level 1 sites within Statistical Area- Level 2 sites to provide targeted samples; and (iii) grouping of contiguous Statistical Area- Level 1 sites or replacing Statistical Area- Level 1 sites to provide sufficient samples.
  
  
  METHODS
  The main outcome measures involved Sites sites selected and participants sampled in the survey.
  
  
  RESULTS
  Thirty sites were generated, including 12 Major City sites, 6 Inner Regional sites, 6 Outer Regional sites, 4 Remote sites and 2 Very Remote sites. Three thousand ninety-eight non-Indigenous participants and 1738 Indigenous participants were recruited. Selection of Statistical Area- Level 1 site overestimated the number of eligible residents in all sites. About 20% (6/30) of Statistical Area- Level 1 sites were situated in non-residential bushland, and 26.67% (8/30) of Statistical Area- Level 1 populations had low eligibility or accessibility, requiring replacement.
  
  
  CONCLUSIONS
  Representative samples of Indigenous and non-Indigenous Australians were selected, recruited and tested, providing the first national data on the prevalence of vision impairment and blindness in Australia.
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.|Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Joshua
authors.initials: J
authors.lastname: Foreman
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.
authors.forename: Stuart
authors.initials: S
authors.lastname: Keel
authors.affiliation: Clinical Epidemiology and Biostatistics Unit, Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, Victoria, Australia.
authors.forename: Ross
authors.initials: R
authors.lastname: Dunn
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.|Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: van Wijngaarden
authors.affiliation: Indigenous Eye Health Unit, Melbourne School of Population and Global Health, the University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Hugh R
authors.initials: HR
authors.lastname: Taylor
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.|Ophthalmology, Department of Surgery, the University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Dirani
mesh_terms: D000328:Adult; D001315:Australia / Q000453:epidemiology; D001766:Blindness / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009313:National Health Programs / Q000458:organization & administration*; D010349:Patient Compliance; D015995:Prevalence; D012307:Risk Factors
keywords: national survey; population health; random cluster sampling