Originally Posted by Oberon

It's not even debatable whether the DPA survey is biased. It is clearly biased and unless the authors have no familiarity with statistics they would say so themselves. Only Delta pilots who go to the DPA website participate and since not all Delta Pilots go to the DPA website it isn't representative of the pilot group. You can argue how exactly that bias affects results but you can't argue the DPA survey isn't biased...unless you have no familiarity with statistics.

For what it's worth the ALPA survey suffers from a similar bias.