Here is a very helpful article on the issue of metrics:
The author claims that not only are most web publishers measuring the wrong metrics, the data they do measure is usually inaccurate.
To the tune of 75%.
Bottom line: figure out what you’re supposed to be measuring (for a sales site, it’s conversion) and measure that.
How many visitors opt in?
How many viewers buy?
What is their average purchase amount and purchase frequency?
Don’t get hung up on the number of page views, except that if you’re getting a bunch of folks clicking away immediately, you know you have a problem. 🙂