It said the population of 2500 "Scientists" was "cientists drawn from the rolls of the science advancement association, which includes teachers, administrators and others involved in science as well as researchers."
Association? Only one? yup, only one: the American Association for the Advancement of Science. That means the members of the "scientist" set is, at least in one demographic, self-selected. AAAS is "open to all" and has become heavily politicized. For example, consider who was the keynote speaker at their 2009 Annual Meeting:
Al Gore speaks at the 2009
AAAS Annual Meeting in Chicago