Questionnaire surveys - sources of error and implications for design, reporting and appraisal

Questionnaire surveys of dentists are a commonly used research method which can yield important results. Nevertheless, in order to give reliable information, surveys must be carefully designed to avoid bias. The challenge of planning, designing and implementing a questionnaire study is often underestimated. While headline response rate is commonly used as an indication of survey quality, there are four potential areas of survey error. These are coverage, sampling, measurement and response. These four areas of error are discussed, with examples from the current literature, to assist readers in critically appraising questionnaire studies. We make 12 key recommendations to researchers to help avoid bias in their research; approaches to response enhancement are also considered. Reporting guidelines for questionnaire studies are suggested which improve transparency and assist in understanding of research methodologies and results. We have termed these guidelines: Reporting Items for Surveys and Questionnaires (RISQ). In conclusion, there is no single solution that can guarantee a successful study. Conversely, failure to pay careful attention to any one of many crucial aspects of survey design can be the downfall of an otherwise robust study.