The questionnaire is the main instrument for collecting data in survey research. Basically, it is a set of standardized questions, often called items, which follow a fixed scheme in order to collect individual data about one or more specific topics. Sometimes questionnaires are confused with interviews. In fact, the questionnaire involves a particular kind of interview—a formal contact, in which the conversation is governed by the wording and order of questions in the instrument. The questionnaire often is administered in a standardized fashion, that is, in the same way to all the respondents of the survey. The logic behind the standardization of questions and answers is that only if a stimulus is the same for all the respondents of a survey can it be, at ...