'based on a true story' can mean at some point in the history of mankind someone wore the same purple pants as the main character. i think it was called 'the last shot,' with alec baldwin and matthew broderick, based on some FBI sting to catch some gangsters by setting up a phony movie production. watching the documentary attached to it, the movie was pretty far removed from what really happened except in a very, very broad sense.
movies 'based on a true story' is rather like reading USAtoday or the enquirer, which re-inforces the old saying, 'newspapers are half rumours, half lies and half truth.'
obviously emily didn't send away for preyer's free exorcism kit, only $19.95. you know, ronald mcdonald has a house to help people out. i think chik-fil-a should have a house for possessed people seeing as how that whole thing is on the rise. avoid taco bell's house, though. trust me. talk about *real* horror....