European Journal of Epidemiology

, Volume 17, Issue 9, pp 809–817 | Cite as

Does non-responder bias have a significant effect on the results in a postal questionnaire study?

  • Jyrki-Tapani Kotaniemi
  • Juhani Hassi
  • Matti Kataja
  • Elsy Jönsson
  • Lauri. A. Laitinen
  • Anssi R.A. Sovijärvi
  • Bo Lundbäck


Background and aim: In epidemiological questionnaire studies results can be influenced by non-responder bias. However, in respiratory epidemiology this has been analysed in very few recently published papers. The aim of our paper is to assess if the results found in our previous postal questionnaire study in an adult population in Northern Finland were biased by non-response. Methods: A random sample of 385 persons from the 1284 non-responders in a previous postal questionnaire study was examined. The same questionnaire as in the original study was again mailed to these persons, and those still not answering were contacted by phone. Results: Totally 183 complete answers (48%) were collected. Lack of interest (56%) and forgetting to mail the response letter (22%) were the most common reasons to non-response. Typical non-responders were young men and current smokers who less frequently reported respiratory symptoms in exercise and asthma than the responders in the original study. Answers collected by phone gave for some questions higher prevalence rates than postal answers. Conclusion: Firstly, in this population the response rate (83.6%) in the original study was high enough to provide reliable results for respiratory symptoms and diseases, only the prevalence of current smoking was biased by non-response. Secondly, the methods used for collecting responses in a non-response study may influence the results.

Adults Asthma Chronic bronchitis Epidemiology Non-responders Respiratory symptoms 


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Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Jyrki-Tapani Kotaniemi
    • 1
  • Juhani Hassi
    • 2
  • Matti Kataja
    • 3
  • Elsy Jönsson
    • 4
  • Lauri. A. Laitinen
    • 5
  • Anssi R.A. Sovijärvi
    • 6
  • Bo Lundbäck
    • 7
  1. 1.Department of Pulmonary MedicinePäijät-Häme Central HospitalLahti
  2. 2.Regional Institute for Occupational HealthOuluFinland
  3. 3.National Public Health InstituteHelsinkiFinland
  4. 4.The OLIN Studies Group, Dept. of MedicineSunderby Central Hospital of NorrbottenLuleåSweden
  5. 5.Dept. of MedicineUniversity HospitalHelsinkiFinland
  6. 6.Division of Clinical Physiology and Nuclear MedicineUniversity HospitalHelsinkiFinland
  7. 7.National Institute of Environmental MedicineKarolinska InstitutetStockholmSweden

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