FWIW, when I moved to SD it was to work with a company that was involved in the health care information business using demographics to forecast health care demand. With the exception of the Census all data is based upon very limited household surveys. Even the Census has its flaws and limitations. We would often look at various suppliers of raw demographic and they were all different. There is no absolutely correct source just a collection of guestimates full of flaws.
Where you stand depends upon where you sit and where I sit people arent drinking powdered milk either.
