title: Telephone versus postal surveys of general practitioners: methodological considerations.
abstract: BACKGROUND
  High response rates to surveys help to maintain the representativeness of the sample.
  
  
  OBJECTIVE
  In the course of a wider investigation into counselling services within general practice it was decided to assess the feasibility of increasing the response rate by telephone follow up of non-respondents to a postal survey.
  
  
  METHODS
  A postal survey was undertaken of a random sample of 1732 general practitioners followed by telephone administration of the questionnaire to non-respondents. The identical questionnaire was administered by telephone to a separate random sample of 206 general practitioners.
  
  
  RESULTS
  Of 1732 general practitioners first approached by mail, 1683 were still in post of whom 881 (52%) completed the postal questionnaire and a further 494 (29%) the telephone interview. Of 206 general practitioners first contacted by telephone, 197 were still in post of whom 167 (85%) completed interviews. Compared with doctors first approached by mail, those first approached by telephone were significantly more likely to report having a partner with a special interest in psychiatry (P < 0.01); and a general practitioner, practice nurse or health visitor who worked as a counsellor (P < 0.01 in each case). A comparison of doctors first approached by telephone with those who completed telephone interviews after failing to respond to the postal questionnaire showed that postal non-respondents were significantly less likely to report having a general practitioner, practice nurse, health visitor or community psychiatric nurse who worked as a counsellor (P < 0.01 in each case).
  
  
  CONCLUSIONS
  These findings suggest that non-response to the postal survey was associated with lack of activity in the study area. Telephone administration of questionnaires to postal non-respondents increased response rates to above 80% but, as telephone administration enhanced the reporting of counsellors, a social desirability bias may have been introduced.
authors.affiliation: Division of General Practice and Primary Care, St George's Hospital Medical School, London.
authors.forename: B
authors.initials: B
authors.lastname: Sibbald
authors.forename: J
authors.initials: J
authors.lastname: Addington-Hall
authors.forename: D
authors.initials: D
authors.lastname: Brenneman
authors.forename: P
authors.initials: P
authors.lastname: Freeling
mesh_terms: D003625:Data Collection; D004739:England; D005194:Family Practice / Q000706:statistics & numerical data*; D006801:Humans; D011177:Postal Service; D013689:Telephone