Chapter 9: Non-experimental Research, Part1: Observational, Archival, and Case-Study Research

The method of non-experimental research that left me piqued was participant-observer research. I wonder about the ethical concerns that arise when a researcher joins a group with a false identity. I would think that as long as the researcher omits any identifying data and doesn't partake in any action(s) that are illegal than what is the problem? I'm sure that there are many deviant groups that exist that can offer much insight in human nature that may be otherwise overlooked if psychologist could be given clearance from the IRB.