OK, I sort of found info on the study, they don't seem to have an official write up, just cliff's notes really - a poll of 1700 people from (ONLY) VA, NJ, and PA is apparently sufficient to say that 90% of our nation wants background checks for every firearm transfer. Check out the question they asked too - VA and NJ residents answered the question: are you in favor of "requiring background checks on people buying guns at gun shows,"... at gun shows. Only PA people answered the question of if they are in favor of background checks for all gun buyers. I'm hoping that there is another source that has better collected evidence to support using the 90% stat.