You could simulate it by recording its position on the front page for each impression. Assume that higher positions on the page are seen more. Then your metric

You could simulate it by recording its position on the front page for each impression. Assume that higher positions on the page are seen more. Then your metric is something like upvotes per position-discounted impression. On the other hand, I'm not sure that dang would get much value out of this kind of metric unless he was trying to tune the ranking algorithm or something like that.