I'd like to add that, much in the way this illness shifts significantly over time, so has my interest/purpose in visiting patient forums.
I think this important fact about this illness, this forum, and life in general--its changeability and continuous state of flux--is the main reason, imo, studies and questionnaires of all kinds are flawed.
Every single survey I have ever filled out I have had to "fudge", because even with "never", "sometimes" "often" or such things, I may have answered totally differently when I was well, in the first three years of the illness, or now. Or six months ago. Or last week. The part of human beings that remains stable and untouched by experiences of illness or wellness is not addressed in surveys.
When I first came to the site, it was entirely to gain scientific insight and treatment information, which was new to me and harder to find elsewhere. Slowly, as I became sicker and more isolated, a sometimes-greater need for social interaction was met here. Both motivations wax and wane even now.
Honestly, with all due respect, I think it is a waste of time and energy to studies/surveys like this. The information culled is automatically skewed and inaccurate because it is trying to make static something which is by its nature dynamic, and trying to quantify something which is unquantifiable in its mutlifaceted, multilayered complexity.
In fact, if one shifts vantage drastically, one can see the forums as just one example of the way in which human beings are a collective intelligence operating in a state of dynamic, spontaneous, seamless collaboration between its differentiated parts for the benefit of parts and whole simultaneously. This would be a most interesting thing to study, perhaps.
Human beings are not merely data. They are not the merely the data they exchange, either. Focusing on the data is a narrowing that almost entirely strips the subject of meaning, even while endeavouring to uncover that meaning.