Warning: I am sort of delirious…
When thinking about web metrics I often ask myself, "what should our target be?" If we have 1 million visits, is that good? If we have 100 visits is that bad?
What if we spent double the amount to drive more traffic, would a good target for the traffic be double? Is there a way to gauge the size of your potential audience through something like market share? And if you did double your traffic, does that actually get you the end result you need?
I often contend that even if you double or triple traffic, doesn't mean you are going to double or triple your sales. I think it all comes back to getting the "right" kind of traffic. There really is no definition of what the right number should be, but the only way to have any insight into where it should be is to look at your ROI on certain tactics, and mimic that behavior across the board.