As researchers, we often collect data on a clinical record form or a questionnaire. It is an important part of study design. If the questionnaire is not well designed, the data collected will not be useful. In this section of the module, we have discussed some practical aspects of designing a questionnaire. It is useful to make a list of all the variables that will be assessed in the study before preparing the questionnaire. The researcher should review all the existing questionnaires. It may be efficient to use an existing standardized questionnaire or scale. Many of these scales are freely available and may be used with an appropriate reference. However, some may be under copyright protection and permissions may be required to use the same questionnaire. While designing their own questionnaire, researchers may use open- or close-ended questions. It is important to design the responses appropriately as the format of responses will influence the analysis. Sometimes, one can collect the same information in multiple ways - continuous or categorical response. Besides these, the researcher can also use visual analog scales or Likert's scale in the questionnaire. Some practical take-home points are: (1) Use specific language while framing the questions; (2) write detailed instructions in the questionnaire; (3) use mutually exclusive response categories; (4) use skip patterns; (5) avoid double-barreled questions; and (6) anchor the time period if required.
Keywords: Categorical responses; questionnaires; scales.