What Web Analytics Can - And Can't - Tell You

"A lot of sites fixate on what their Web analytics, packages like Google Analytics and Ominiture, tell them. They look at stats on 'page views,' 'visits' and 'unique visitors' and measure their progress in terms of how much traffic increases over time.

"They might look at 'engagement' stats like 'time on site' and 'page views per visit' to glean how much people are enjoying the site after they come in for their visit.

While those stats can be a fine way to get a handle on relative growth, they're not true measures of the number of people coming to a site. And they're also measures that many advertisers won't accept."

Poynter Online - E-Media Tidbits: What Web Analytics Can - And Can't - Tell You about Your Site's Traffic and Audience (by Dorian Benkoil)