title: Estimates of intraclass correlation coefficient and design effect for surveys and cluster randomized trials on injection use in Pakistan and developing countries.
abstract: BACKGROUND
  To assess injection practices and to test interventions aimed at reducing unsafe injections in developing countries, cluster surveys and cluster randomized trials are needed. The design of cluster-based studies requires estimates of intraclass correlation coefficients that have to be obtained from previous studies. This study presents such estimates.
  
  
  METHODS
  Data were derived from a cross-sectional study of injection use and health seeking in Pakistan that used 34 clusters to select 1150 study subjects aged > or =3 months. We analysed variance to separate its components.
  
  
  RESULTS
  Most of intraclass correlation coefficients were in the range of 0.01-0.05. For proportion of injections received during last 3 months, mean number of injections received and health seeking during the past 3 months the intraclass correlation coefficients were 0.02, 0.04 and 0.02, respectively.
  
  
  CONCLUSIONS
  These estimates can be useful in designing cluster surveys and cluster randomized trials for injection safety in Pakistan and other developing countries.
authors.affiliation: Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan. naveed@uab.edu
authors.forename: Naveed Zafar
authors.initials: NZ
authors.lastname: Janjua
authors.forename: Mohammad Imran
authors.initials: MI
authors.lastname: Khan
authors.forename: John D
authors.initials: JD
authors.lastname: Clemens
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002983:Clinical Competence; D003906:Developing Countries; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007223:Infant; D007267:Injections / Q000009:adverse effects / Q000592:standards / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010154:Pakistan; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data; D012107:Research Design; D012423:Rural Health / Q000706:statistics & numerical data; D012959:Socioeconomic Factors; D014504:Urban Health / Q000706:statistics & numerical data