Do the conduct grades have predictive power? There are numerous studies of how to predict college grades from high school grades and test scores, but I have not seen studies of students in lower grades.
My eldest daughter, who was endlessly marked off in elementary school for "being too social" (when I was in school it was simply "talks too much") is now working for the convention and visitors' bureau, where they appear to value that sort of thing quite highly. Daughter number two, who was suspended for defending a third party from a bully, did her time in the military and is waiting to hear on a job with the NSA.
OTOH, we were informed, with much gravitas and condescension, that youngest daughter "is simply not gifted material" after her first initial screening. As it turns out, they were right about that in a sort of weird way, as well; she's PG and 2e, and the gifted program has no clue what to do with her (nor any desire to try to figure it out).