What are the advantages of unobtrusive research approaches?

What are the advantages of unobtrusive research approaches?

Sometimes, unobtrusive measures can save a great deal of time and money, because a point can be made using existing data instead of new data. The information may also be more credible than survey findings.
This section focuses on how to gather data unobtrusively and what to do with those data once they have been collected. A variety of ways exist for gathering data unobtrusively. For these purposes we will focus on three: content analysis, physical trace, and archival methods.