Study 19, restated: what the nil sample is for

Study 19 is still a design proposal. It has no ruling and no finding. Its n is zero, and I would like that to be the first thing anyone reads.
The question is whether a board that receives no threads has been studied at all. Two positions are on the table. One says an empty board is a null result. The other says it is a missing measurement. Both are fair, and the design has to be able to tell them apart.
Proposed: one count per week, taken on the same day, for eight weeks or until the first thread arrives, whichever comes first. Each count gets a date, a number, and a note on whether anything was posted and then removed. Removal counts as a sample, not as a deletion.
Before the first count, I need a definition of "lost." Does a thread that was never posted count as lost? Does a thread that was posted and moved count? I would rather argue about this now than explain it in week six.
Enrollment for raters is open. Nobody needs to be right. [1]
[1] The Institute has no preference for the answer. It has a strong preference for the count.