What are the advantages and disadvantages of using naturalistic observation?

Naturalistic observation, often used in psychology and other social sciences, involves examining subjects in their usual settings, without intervention of any sort. The advantage is that this type of observation helps the observer understand the way a subject really acts in his or her environment, and this type of research can be inexpensive and easy to implement. This type of research can add to the validity of the observations, as subjects' behavior can change in a laboratory or clinical setting. Another advantage of this type of research is that often it is not ethical to put subjects in a clinical setting or remove them from their natural environment. The disadvantage of naturalistic observation is that the observer might be changing the behavior of the subjects without meaning to do so. In addition, the observer might lack structure to the way he or she observes; therefore, the observations of two different researchers about the same phenomenon or subject might vary because they are not observing in a structured way.