title: How does a change in the administration method affect the reliability of the COOP/WONCA Charts? World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians.
abstract: BACKGROUND
  An interviewer is often needed to administer the COOP/WONCA Charts to Chinese patients, and this may affect the reliability of results.
  
  
  OBJECTIVE
  We aimed to find out the reliability of the COOP/WONCA Charts administered by an interviewer, and whether a change in the interviewer or administration method would affect the results.
  
  
  METHODS
  We carried out a cross-sectional test-retest study on 487 Chinese adult patients attending a family medicine clinic in Hong Kong. The COOP/WONCA Charts were administered by the same interviewer, two different interviewers or self-completion and interviewer administration, on test and retest. The random, inter-observer and inter-method variances were compared with the inter-subject variance. The reliability coefficient of each COOP/WONCA Chart was calculated for each method of administration.
  
  
  RESULTS
  Random errors could change the scores by 0.57-1.04, inter-observer variations could change the scores of four charts by 0.72-0.80, and a change in the method could change the physical fitness score by 1.79 and the daily activities score by 1.31, on a five-point scale. The reliability coefficients of the six COOP/WONCA Charts were 0.68-0.92 for one interviewer, 0.59-0.82 for two interviewers and 0.46-0.81 for two methods.
  
  
  CONCLUSIONS
  The Chinese COOP/WONCA Charts were reliable in detecting real differences when administered by an interviewer. A change in the method of administration significantly decreased the reliability of the results. The use of more than one method of data collection in the same survey should be discouraged.
authors.affiliation: General Practice Unit, Ap Lei Chau Clinic, Hong Kong.
authors.forename: C L
authors.initials: CL
authors.lastname: Lam
authors.forename: I J
authors.initials: IJ
authors.lastname: Lauder
authors.forename: D T
authors.initials: DT
authors.lastname: Lam
mesh_terms: D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D044466:Asian People; D003144:Communication Barriers; D003430:Cross-Sectional Studies; D005194:Family Practice / Q000379:methods; D005260:Female; D006304:Health Status; D006723:Hong Kong; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008499:Medical Records / Q000592:standards*; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012737:Sex Factors; D011795:Surveys and Questionnaires