What is one major limitation of observational data collection technique? When you respond, please give an example of such observational data collection tool. Your example needs to be different from any example given in your textbook or in my lecture.

What is one major advantage of unobtrusive observation over other types of data collection? When you respond, please give an example of such unobtrusive observation data collection technique. Your example needs to be different from any example given in your textbook or in my lecture.