Re-reading your comment, perhaps I misinterpreted it. > So now we know that a #1 post on HN has about ~450 concurrent visitors I thought you were trying to ge

Re-reading your comment, perhaps I misinterpreted it. > So now we know that a #1 post on HN has about ~450 concurrent visitors I thought you were trying to get a measure of traffic to HN. In that case, the number of visitors to the site is only an approximation. But if you were talking about how much traffic HN directs to the #1 post, then the number is exactly correct.