What is an example of secondary data analysis? Why might we use it? What are the pros and cons of using it?

Secondary data comes from a source other than the researcher. (Primary data, by contrast, is that which the researcher collects for his or her own study.) Examples include government census reports, other governmental databases, and administrative data.

Researchers are often drawn to the time and cost saving benefits of using secondary data. Secondary data may also provide information the researcher would not have access to alone. This type of data is usually essential in studies of change over time because it can provide information that cannot currently be collected. Secondary data may also provide larger, higher quality information than the researcher could gather independently. Secondary data can also be used to establish a baseline to design new research and compare new data. Another advantage to using secondary data is the information may already have been vetted for reliability and validity, saving the researcher a step in the process. 

A disadvantage of using secondary data is that the information may be out of date or no longer relevant. Additionally, since the data already exists, the researcher is not able to manipulate particular variables to specifically address research questions. Another problem is the data available may not be representative enough or detailed enough to serve the researcher’s purposes.