Care should always be taken to only use previous data when it is methodologically important to do so. Here are the 5 times that reusing data to enhance your survey is actually ok.
When you find yourself surveying a population where significant information is known about those who are in the study prior to them completing the survey (such as in a longitudinal survey, a panel, or when the respondents are part of a known group such as a membership organization), such data can be used as part of the survey instrument design.
While it is tempting to do whenever possible, when using such data, care should be given to how and when it is used…