If you are observing faculty members in a teachers’ lounge, are you interested in who speaks with whom, or are you also interested in who initiated the conversation? Who initiated the conversation and who responded might be more interesting than just recording the pairs of teachers who engaged in conversations.
This is certainly applicable to my own study. My original thought was that my data could be undirected, but I'm now questioning that. For example, it would be interesting to see if an initial contact between two students was then reciprocated, or if there were other contacts that seemed to follow from the initial.