Ethnography?
Ethnography originates from anthropology, and is used to study cultural groups. It's meant to represent the voices of the group members, but also to be reflexive, and to make a contribution to the understanding of that cultural group.
The key terms here are understanding and representing. Ethnography is meant not to change how people behave but to learn from them. Often it isn't meant to do any more than that, but in libraries, if we use ethnographic based methods, we can use them to ask the right kind of questions of libraries, change what we do to support the way people work. For us, it's about improving user experience, if we can.
It can also be approached from a critical perspective, looking at power relations or under-represented groups, something that is becoming increasingly common in library ethnography (see Penny Andrews' contribution to the Priestner/Borg edited User Experience In Libraries, due out in 2016, in particular)