In creating a questionnaire for an epidemiologic study ...



Creating a Questionnaire for an Epidemiologic Study

(Adapted from UNC School of Public Health, Focus on Field Epidemiology, Vol. 2, 2.)

Steps in creating a questionnaire:

1. Identify the leading hypotheses about the source of the problem.

2. Identify the information needed to test each hypothesis.

3. Identify the information needed for the logistics of the study and to examine confounding factors.

4. Write the questions to collect this information.

5. Organize the questions into questionnaire format.

6. Test the questionnaire.

7. Revise the questionnaire.

8. Train interviewers to administer the questionnaire.

In creating a questionnaire for an epidemiologic study, investigators typically follow the steps shown above. One of the most common errors in questionnaire development is to start by writing the questions. The first step in creating a questionnaire is actually to identify the leading hypotheses about the source of the problem. You can then identify the information needed to test each hypothesis and identify the information needed for the logistics of the study and to examine confounding factors. Only after you have identified the information you need are you ready to write the questions and organize them into a questionnaire.

An epidemiologic questionnaire typically includes five categories of information:

o identifying information

o demographic information

o clinical information

o exposure or risk factor information

o source of the information

Once you have identified the information you need, you can begin writing the questions. The exact wording of questions depends on your knowledge of the problem, the hypotheses being tested, the kind of information you wish to collect, and the affected population. Therefore, it will be different with each epidemiologic investigation. Along with general considerations for questionnaires, some generalizations can be made about the types of questions and their construction. Three types of questions are used in questionnaires for epidemiologic studies:

o Open-ended questions

o Used when researchers are interested in a topic but the answer cannot be as clearly defined as other types of questions allow and/or when the researcher doesn’t know what answers they will get. While it is difficult to turn answers from open-ended questions into a binary (Yes/No) form or another type of short form (1-5), the responses can often help the investigators develop new hypothesis that can be explored in more detail at a later time.

o Fill-in-the-blank questions

o Used when researchers have a better idea about what information they’re looking for but the respondent will need some leeway to answer. Questions where a comprehensive list of categorical responses (below) would be too long often use a fill-in-the-blank structure.

o Closed-ended questions

o Used when the researcher has a very definite idea about what information is needed. Closed-ended questions make the respondent answer in a specific way and are therefore the easiest to turn into binary or another type of short form. Responses on early surveys from open-ended and fill-in-the-blank may become closed-ended questions in later surveys. These questions can appear in two forms

▪ With categorical response options – where a short list of options is provided and the respondent selects one or more of the options.

▪ With ordinal (numbered) response options – where respondents select a numeric rating based on like/dislike, frequency, or other criteria.

In general, a questionnaire should be as short as possible and should focus on the hypotheses being tested in the study. A lengthy questionnaire uses a lot of resources and tires respondents. Focus on your leading hypotheses and the particular pieces of information you need to test these hypotheses. Then try to strike a balance between testing the hypotheses and taking advantage of opportunities to gather ‘extra’ information that is of interest to the investigation.

In an epidemiologic investigation, it is sometimes difficult to know how to form the right questions, let alone understand the answers. By carefully framing and refining the hypotheses under investigation and knowing what information is needed to test those hypotheses first it is easier to develop a series of open-ended, fill-in-the-blank, and closed-ended questions to obtain the needed information. Keep in mind the nature of an epidemiological study and pay careful attention to the specific wording and organization of the questionnaire.

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