Question

Recording all instances of an event for a particular time period (such as how many times an older brother strikes his younger brother) without the subjects' awareness is an example of:

Answer 1

I believe the answer is: naturalistic observation

Naturalistic observation is being done without any form of variable manipulation from the researchers. The purpose of such observation is to make the result of the study represent the actual condition as close as possible. Usually only applicable for qualitative data.