claaarky - 8:59 pm on Jun 25, 2012 (gmt 0)

Thanks for all the thoughts so far.

The consensus at this stage seems to be that:-
a) Google is collecting very sophisticated user metrics probably via the browser and feeds that into Panda to determine whether your site has a big enough problem with bad content that your site should be demoted to protect users from coming into contact with it.
b) Exit Rate may be one of the many metrics Panda looks at to identify low quality content, but the importance of it may depend on the type of site you have.
c) Time on page may be important, but again it depends on the type of site.
d) Any stats you use to help identify pages with bad content on your site should be viewed keeping in mind the type of page (if your page is an article that takes 3 minutes to read you would expect the average time on page to be around that - if there's a second page you would expect the exit rate to be low, and so on). If your stats show the average user spent 5 seconds on the page and then left, there could be a quality issue with that page. Look at it, work out why, fix it or remove it, repeat until all content is great and you escape Panda.

So is anyone with a healthy site willing to share some statistical information about their site so we can see what a healthy site of that type looks like in statistical terms?

These are my stats for May 2012 to give you the idea, but my site is affected by Panda so please don't use this as a model for your site!
1) Type of Site: Ecommerce (hit by Panda)
2) Home page: exit rate 35%, average time on page 1.08, bounce rate 35%
3) Category pages: exit rate (15-35%, average 30%), average time on page (30-60 seconds, average 50 seconds)
4) Product pages: exit rate (2-75%, generally around 15%), average time on page (max 2 minutes, average 50 seconds)
5) Proportion of pages with exit rate higher than 30%: 25%
6) Proportion of pages with average time on page of less than 20 seconds: 20%

I'm working on the basis that for my type of site, I don't want more than 30% of my visitors leaving the site from any product page and that it would take a customer at least 20 seconds to take in the product description. My stats show that a third of my product pages are performing worse than this.

I know Google stats will be a tad more sophisticated than this, but there has a to be a statistical shape sites need to be to fit the profile Google have for each type of site. If we know that, anyone affected by Panda has something to aim for when sorting out their content.