I think that experiences can offer different levels of validity to a discussion regardless of qualifications, I don't think they should be just pushed to one side becuase they can't be backed up with hard scientific proof, I think personal observations are very important, that's part of science, most doctors well tell you that they beleive there is a connection from their observations but they can't prove it conclusively, but that doesn't mean that those observations should go unwarranted, and you don't always have to be 'qualified' to know that there is a connection between the two, but obviously proving it is another matter.