Questionnaires are one of the most important tools for field epidemiologists. An advantage of using a questionnaire is that it enables you to reach a large number of persons at once. On the other hand, using a questionnaire might be a disadvantage if you have little information on the subject and do not ask the right questions.
Questionnaires are used in outbreak investigations, and applied research as well as in evaluation of surveillance systems. The success of an investigation or a research project largely depends on a high response from the target population and the amount of valid information that was obtained.
There are different types of questionnaires: Questionnaires can either be filled out by the respondent (self-administrated) or by an interviewer in a telephone or a face-to-face interview (interviewer-administrated). The suitable format depends on the study question, the target population and the available resources. Similarly, there are different types of questions, open and closed. Answers to open questions will provide you with additional information and comments which you might have considered beforehand. Closed questions provide a limited choice of answers and are therefore easy to analyse.
A well designed questionnaire will provide appropriate data which allow answering your research question. It will minimise potential sources of bias, thus increasing the validity of the questionnaire. A well designed questionnaire is much more likely be completed. Therefore, creating a good questionnaire is crucial for the success of your project.
This chapter should help you to distinguish between the different types of questionnaires, questionnaire administration and question formats. You can follow the 10 steps for designing a questionnaire or check the quality of your questions with the useful hints that are given. For example, the seven golden rules will guide guide you perfecting your questionnaire. You can also find useful information on piloting questionnaires and validated questionnaires.