Which type of study would require Institutional Review Board (IRB) approval?

The correct answer highlights that studies collecting identifiable information about living individuals necessitate Institutional Review Board (IRB) approval due to the ethical concerns and potential risks associated with handling private data. When research involves gathering information that can be traced back to individuals, it raises issues related to privacy, consent, and the potential for harm. IRB oversight ensures that these studies are designed responsibly, protecting the rights and welfare of participants.

In contrast, observational research of public behavior doesn’t typically involve identifiable data, which reduces privacy concerns and, therefore, often doesn't require IRB review. Anonymous surveys, when conducted in a way that ensures no identifying information is collected, similarly may not necessitate IRB approval, as they don't pose the same ethical implications. Research involving historical documents also usually does not require IRB review because it deals with public or non-living subjects, focusing on data that is not sensitive or proprietary. Thus, the high-level ethical standards set by the IRB come into play specifically for studies that involve direct interaction with living individuals and their personal information.