I've heard the same things about Peterson's data, knowing the college data industry (I worked in that industry for about five years). I'd suggest looking at a website like gradcu.com or the school websites that you're most interested in. They are way more focused on the graduate education and should have the most up-to-date information that you're looking for. Gradcu.com data is updated yearly no matter what, so everything is current. It's also more of a holistic site that doesn't put a ton of emphasis on test scores or selectivity in the grad school arena.
