Research techniques employing questionnaires, interviews, and psychological tests all involve confronting individuals with situations that are, to a considerable extent, outside their daily rounds of living. Thus the researcher interposes some kind of stimulus – whether a set of questions or a performance task – assumed to be in some way an analogue of ordinary behavior. The researcher assumes that habitual behavioral tendencies of subjects will be reflected in reactions to the situations structured by the anthropologist. Even informal conversations between anthropologists and research subjects are “obtrusive” in that the anthropologist is to some extent an outsider in the research community. On the other hand, anthropological field work involves observation that is “unobtrusive” whenever the anthropologist watches ongoing behavior – feasts and festivals, daily work, meetings and discussions, recreation, and other habitual activities.

Under the heading of “participant observation” we generally include a wide range of informal and formal materials, which often makes up a large portion of the fieldworkers' field notes. A frequent complaint about ethnographic reporting is that direct eyewitness information is completely mingled with secondhand, hearsay data (cf. Silverberg, 1975). Marvin Harris's discussion of etic ethnography (Chapter 4) represents an attempt to systematize observational data gathering in order to overcome this weakness.