It looks as if I have to rethink my dissertation. This isn't a big surprise - I knew my original idea might prove impervious to research, but my committee and I decided to attempt it anyway. Now I either have to scale way down or pick a new topic. It's probably going to be the former.
There are two opposing ideas about dissertations. In one model, "the best dissertation is a done dissertation." In the other, your dissertation is your journeyman work piece, showing what you are capable of. Most dissertations lie somewhere in between; after all, a dissertation won't pass and therefore be done unless it reaches some level of quality. If only one person responds to your survey, you can't say, "Oh well, I'm gonna write it up and be done!"
A good metaphor for the dissertation is to think of a jeweler making a ring. (What do I know about gemology? Nothing.) Part of the process involves choosing a stone - first the type, and then the specific one. Shale isn't hard enough, for example. You could use granite; it's tough, but you can't see by looking at it how strong it is. There could be a flaw in the heart of that particular stone. So diamond is good, or emerald, something both strong and easily evaluated. But a good stone is only the start. It has to be cut and set - no super gluing a hunk of rock to a ring! This is where "the best is done" part comes in. It's OK if the stone could use a little extra polish or maybe the setting is plain. But what you clearly have is a ring, and it's well-made.
What I seem to have done is planned to use a terrific type of stone that is now unavailable. I could use a cheap imitation, or choose another stone altogether. This may be taking the metaphor too far. In any case, I now need to pick a new dissertation topic.