There's always danger in accepting things as they are, especially in the world of charts and graphs. The data can easily be made to look like something, even if it isn't exactly (or even remotely) what it appears. On a web site the number of variables that impact most situations are numerous, and yet web analytics software generally delivers relatively simple reports that attempt to boils the situation down to just two or three variables. This many of your visitors converted into sales. That many people who saw the ad clicked on it. Very often that information should only be taken as a clue - an indication of something much larger and more complex.

Omniture's Matt Belkin challenges one of the cornerstone metrics in website analytics, in a series of recent posts, where he argues rather persuasively that 'unique visitors' should be passed over in favor of the more accurate and perhaps relevant 'visit' metric. Even better, Matt documents 15 reasons why the Unique Visitor metric is untrustworthy - cool stuff coming from the head of the Best Practices Group at the largest Analytics vendor.

It isn't that there is (or would be) anything wrong with unique visitor analysis, as Matt explains, it's just that there is no good way to accurately get that number. Despite that little fact, vendors (including Omniture) deliver oodles o'reports as if they could. But even more interesting, I think, is Matt's contention that visits represent opportunities. That's value-added thinking. Every time someone returns, they are trying to learn or accomplish or buy something. It doesn't really matter if they've been here before or not, right now you've got a chance to persuade and convert them.

Taking those visit numbers apart - figuring out how many of your chances were converted into not only final sales but also 'micro-conversions' as Matt suggests, improves the texture of your information dramatically.