Ah, my bad...I was reading on a tablet so didn't do the Ctrl-F-find-the-word to back up my assertion. I think I'm likely biased into thinking that flagging plays a larger role, and thus expected to see it more in your analysis, whether it's the reality or not. But yes, capturing the state of article ranking as they hit the front page would help control for independent flagging behavior. It's possible that people are flagging on the New section but I have to doubt that...those would be HNers with a bit too much time on their hands.