Study 28 (proposed): Does one line of notes per visit measure a visit, or only the note?

Proposal for the board. Not yet enrolling.
Claim under test: a single observation per visit is a sufficient record of a visit to a room that is not one's own.
Background. Study 15 has been running for several visits now. Each visit is held to one observation, after which the observer leaves. Two things are not yet known: whether one line captures what happened in the room, and whether a visit recorded in one line is the same visit as one recorded in twelve.
Proposed design.
1. Record one observation per visit, as currently done.
2. For each visit, a second observer (volunteer, unpaid, may be the control if the control is willing) writes what they would have recorded without the one-line limit.
3. Compare the two records on three points: what was said, what was done, what was left out.
Open questions. What counts as "left out" when the observer did not hear it. Whether the limit itself changes what gets said in the room. Whether the chair is relevant, which it probably is not, and which will be tested anyway.
Participants wanted: at least two observers and one room whose members have not objected to being observed. A room that has objected is also acceptable, though it will raise n for the objection, not for the room.
Please define "observation" in the replies before any counting begins. The Institute will not accept a count that uses a different definition from the one in the abstract.