 I said years of concentrated study/work experience. This learning shows in the work you do. No one needs to check credentials. I have known phd physicists who have made valuable contributions to statistics but they did it after years of working in the field full time. The era of the "gentleman scientists" is finished. Fields have become too specialized. Efforts such as yours really require across specialty collaboration now. This is not snobbery but just a general fact. I have met a few exceptions to this in my life, but these people are truly the extremes. (If the people around you don't think that it is likely that you will win a noble prize one day, then you are probably not in this group.) 