Designing a questionnaire: Send a personal covering letterBMJ 1994; 308 doi: https://doi.org/10.1136/bmj.308.6922.202c (Published 15 January 1994) Cite this as: BMJ 1994;308:202
EDITOR, - In writing about designing a questionnaire D H Stone only briefly mentions a covering letter for postal questionnaires.1 The importance of such letters has been debated: one experiment found no significant difference in response rate between a sample of people sent a relatively impersonal letter and a sample sent a relatively personal letter.2 Another study found that the response rate to a questionnaire was significantly higher when the covering letter was written by the patient's general practitioner than when it was written by a doctor in a research unit.3 It seems sensible to devote attention to the covering letter, making it personal and attractive and stating the purposes and sponsorship of the study and why the respondent's views are particularly sought. Clear instructions and examples should be given, and a statement about confidentiality should be included.4
Cartwright has written of the problems of writing about the design of questionnaires without stating the obvious,5 yet poorly designed questionnaires are common, create irritation, and waste resources. Departmental audit of questionnaires can be educational and can be used to set standards and devise a quick checklist against which new questionnaires can be compared and audited.
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