The term case refers to one specific element in the population of interest that has been sampled for a survey. A "completed" case contains the responses that were provided by that respondent for the questionnaire used in that survey. A case may be an individual, a household, or an organization. Being able to identify each individual respondent can be critical for the conduct of the survey. Assignment of a unique case number identifier associated with each individual sampled element should be done in every survey. Although most computer-assisted surveys assign a respondent number, it should not be confused with assignment of a case number. As a general rule, case numbers are assigned before a questionnaire is distributed, while respondent numbers are assigned when a respondent ...