title: [Reliability of measurement and the methods of estimating reliability].
abstract: OBJECTIVE
  To explore the methods of estimating measurement reliability and their limitations.
  
  
  METHODS
  According to the given examples, reliabilities of measurement were calculated and limitations of the methods of estimating reliability were analyzed.
  
  
  RESULTS
  The Kappa value of interobserver reliability was 0.793 between two pathologists. Between the two populations with different prevalence rates, the values of Kappa were 0.800 and 0.137 respectively, and with big difference. Cronbach's alpha coefficient of compositive index for A type behavior was 0.55.
  
  
  CONCLUSIONS
  The Kappa index and alpha coefficient were both inherently population-specific. Before generalizing to different populations, the reliability needs to be measured.
authors.affiliation: The Department of Epidemiology, School of Public Health, Fudan University, Shanghai 200032, China.
authors.forename: Yi-biao
authors.initials: YB
authors.lastname: Zhou
authors.forename: Gen-ming
authors.initials: GM
authors.lastname: Zhao
mesh_terms: D000465:Algorithms; D003625:Data Collection / Q000379:methods* / Q000706:statistics & numerical data; D015991:Epidemiologic Measurements; D015588:Observer Variation; D015203:Reproducibility of Results; D013997:Time Factors