For a long time now, the popularity of a website has been determined by how many pages are viewed, and how many unique visitors hit the site.  The higher your numbers, the more popular/valuable your site was.  At least that was the idea up until very recently.  Now, ratings firm Nielsen/NetRatings has announced they will be considering a completely different number to determine the success of a website: Time spent per visit.

The idea is that the longer a user spends at a site, the more worthwhile the content is, especially in the age of Web 2.0 sites that are more quick aggregators of data than anything else.  Things like AJAX sites which refresh content on a page without reloading it, make tracking page views very difficult.  This shift to focus on time spent more than on clicks means there may be a pretty big shakeup for ranking sites like Alexa.

Looks like web metrics are shifting to look at quality over quantity.