Good question. I'd be surprised if they have since they are not necessarily interested in statistical data. As I mentioned above, the survey sent to all pilots is democratic, not necessarily scientific. ALPA, or any representative body for that matter, is probably more concerned with how their participating constituents feel rather than how a statistically significant part of their constituency feels. That's just how democracy works.

It's possible the participation numbers of the ALPA survey will be high enough to make it both democratic and statistically significant but I doubt it. A democratic survey means those who participate are heard. If you care how your democracy represents you you would be remiss not to participate.