Secondary Data

Researchers in epidemiology and public health commonly make a distinction between primary data, data collected by the researcher for the specific analysis in question, and secondary data, data collected by someone else for some other purpose. Of course, many cases fall between these two examples, but it may be useful to conceptualize primary and secondary data by considering two extreme cases. In the first case, which is an example of primary data, a research team collects new data and performs its own analyses of the data so that the people involved in analyzing the data have some involvement in, or at least familiarity with, the research design and data collection process. In the second case, which is an example of secondary data, a researcher obtains ...