There are two reasons that make it increasingly difficult for page-view to be a good metric to compare across sites. First is in-page ajaxy activity. For example, on SlideShare you can download powerpoint file, add slideshow as a favorite and comment without going to another page. The second reason is related to consumption of multimedia content such as video and slideshows. A user might watch a slideshow for a while without impacting page views in any manner.
What can replace the page view? Neilsen moved from page views to time on site as a core metric last July. Now they say that the impact has been greater for video sites than sites with a lot of ajax. A new web metrics startup Nuconomy measures things like number of comments, downloads etc. to track engagement.
At SlideShare, we are starting to use “No of clicks per visit” as a measure of engagement. I like it more than time per visit, since it gives an index of activity on the site. At the same time it takes the multimedia viewing and ajaxiness of the site into account.What do you think about “No of clicks per visit” as a metric?