One of the most popular methods for collecting descriptive or subjective data is the survey approach. A survey is composed of a series of questions that are posed to a group of subjects, and may be conducted as an oral interview or as a written or electronic questionnaire. Sometimes the data are intended for generalization to a larger population; other times they may be intended as a description of a particular group. Surveys in clinical research are often concerned with describing current practices, attitudes and values, or characteristics of specific groups. For example, survey questionnaires have been used to compare the effectiveness of medication, acupuncture and spinal manipulation for chronic low back pain,1 to study physicians' attitudes and practices toward disclosure of prognosis for terminally ill patients,2 and to describe the demographics and injury characteristics of patients with spinal cord injury.3 Standardized questionnaires are also used extensively as instruments for assessing outcomes related to function, health status and quality of life. As these examples illustrate, survey data can be used in experimental, exploratory or descriptive studies.
The purpose of this chapter is to present an overview of the structure of survey instruments. We discuss essential elements of survey design, question writing, and some special assessment techniques associated with questionnaires, including several measurement scales.
INTERVIEWS AND QUESTIONNAIRES
In an interview the researcher asks respondents specific questions and records their answers for later analysis. Interviews can take a few minutes or several hours, depending on the nature of the questions and the respondent's willingness to share information. Interviews can be conducted face to face or over the telephone, although face-to-face interviews tend to be more effective for establishing rapport between the interviewer and the respondent. This interaction can be important for eliciting forthright responses to questions that are of a personal nature. The advantage of the interview approach is the opportunity for in-depth analysis of respondents' behaviors and opinions because the researcher can probe responses and directly observe respondents' reactions. The major disadvantages of interviews include cost and time, the need for personnel to carry out the interviews, scheduling and the lack of anonymity of the respondents.
Most interviews are structured in that they consist of a standardized set of questions that will be asked. In this way, all respondents are exposed to the same questions, in the same order, and are given the same choices for responses. In an unstructured interview, the interviewer does not have a fixed agenda, and can proceed informally to question and discuss issues of concern. This format is typically conversational and is often carried out in the respondent's natural setting. Many qualitative studies use the unstructured interview approach to generate data.
Questionnaires are structured surveys that are self-administered using pen and paper ...